diff --git a/dom/base/MessageManagerCallback.h b/dom/base/MessageManagerCallback.h
index cc6be3f94509a..df2cf047d380c 100644
--- a/dom/base/MessageManagerCallback.h
+++ b/dom/base/MessageManagerCallback.h
@@ -7,12 +7,19 @@
 #ifndef dom_base_MessageManagerCallback_h__
 #define dom_base_MessageManagerCallback_h__
 
+#include "nsError.h"
 #include "nsStringFwd.h"
 #include "nsTArrayForwardDeclare.h"
 
 namespace mozilla {
+
+class ErrorResult;
+
 namespace dom {
 
+class ClonedMessageData;
+class ContentChild;
+class ContentParent;
 class ProcessMessageManager;
 
 namespace ipc {
diff --git a/dom/base/Pose.h b/dom/base/Pose.h
index 4ca5df1e082e7..803574e28cf8a 100644
--- a/dom/base/Pose.h
+++ b/dom/base/Pose.h
@@ -7,6 +7,8 @@
 #ifndef mozilla_dom_Pose_h
 #define mozilla_dom_Pose_h
 
+#include "js/RootingAPI.h"
+#include "nsCOMPtr.h"
 #include "nsWrapperCache.h"
 
 namespace mozilla {
diff --git a/dom/base/TextInputProcessor.h b/dom/base/TextInputProcessor.h
index 29c476b9be5b0..10e0421953196 100644
--- a/dom/base/TextInputProcessor.h
+++ b/dom/base/TextInputProcessor.h
@@ -8,6 +8,7 @@
 #define mozilla_dom_textinputprocessor_h_
 
 #include "mozilla/Attributes.h"
+#include "mozilla/BasicEvents.h"
 #include "mozilla/EventForwards.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/TextEventDispatcher.h"
diff --git a/dom/base/nsGlobalWindowOuter.h b/dom/base/nsGlobalWindowOuter.h
index 409a78e9dcaf8..31c0965aed307 100644
--- a/dom/base/nsGlobalWindowOuter.h
+++ b/dom/base/nsGlobalWindowOuter.h
@@ -50,6 +50,7 @@
 #include "mozilla/dom/ImageBitmapSource.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/dom/BrowsingContext.h"
+#include "X11UndefineNone.h"
 
 class nsDocShell;
 class nsIArray;
diff --git a/dom/canvas/WebGLTexelConversions.h b/dom/canvas/WebGLTexelConversions.h
index 478b88c82f6d1..859a25667ca0e 100644
--- a/dom/canvas/WebGLTexelConversions.h
+++ b/dom/canvas/WebGLTexelConversions.h
@@ -39,6 +39,10 @@
 
 namespace mozilla {
 
+namespace gl {
+enum class OriginPos : uint8_t;
+}
+
 bool ConvertImage(size_t width, size_t height, const void* srcBegin,
                   size_t srcStride, gl::OriginPos srcOrigin,
                   WebGLTexelFormat srcFormat, bool srcPremultiplied,
diff --git a/dom/events/DataTransferItem.h b/dom/events/DataTransferItem.h
index 48c6784f7df70..ceeb802a15b83 100644
--- a/dom/events/DataTransferItem.h
+++ b/dom/events/DataTransferItem.h
@@ -16,6 +16,7 @@ class ErrorResult;
 
 namespace dom {
 
+class DataTransfer;
 class FileSystemEntry;
 class FunctionStringCallback;
 
diff --git a/dom/events/DataTransferItemList.h b/dom/events/DataTransferItemList.h
index 43b477943a79a..d30093ec6256a 100644
--- a/dom/events/DataTransferItemList.h
+++ b/dom/events/DataTransferItemList.h
@@ -11,9 +11,12 @@
 #include "mozilla/dom/DataTransferItem.h"
 #include "mozilla/dom/FileList.h"
 
+class nsIVariant;
+
 namespace mozilla {
 namespace dom {
 
+class DataTransfer;
 class DataTransferItem;
 
 class DataTransferItemList final : public nsISupports, public nsWrapperCache {
diff --git a/dom/events/PendingFullscreenEvent.h b/dom/events/PendingFullscreenEvent.h
index 68cafd3dd165c..afd5e73b8327a 100644
--- a/dom/events/PendingFullscreenEvent.h
+++ b/dom/events/PendingFullscreenEvent.h
@@ -7,6 +7,7 @@
 #ifndef mozilla_PendingFullscreenEvent_h_
 #define mozilla_PendingFullscreenEvent_h_
 
+#include "mozilla/dom/Document.h"
 #include "nsContentUtils.h"
 
 namespace mozilla {
diff --git a/dom/file/MutableBlobStorage.h b/dom/file/MutableBlobStorage.h
index 9c22150ec6e61..6bacaa9de42e6 100644
--- a/dom/file/MutableBlobStorage.h
+++ b/dom/file/MutableBlobStorage.h
@@ -10,6 +10,7 @@
 #include "mozilla/RefPtr.h"
 #include "mozilla/Mutex.h"
 #include "nsCOMPtr.h"
+#include "nsString.h"
 #include "prio.h"
 
 class nsIEventTarget;
diff --git a/dom/gamepad/Gamepad.h b/dom/gamepad/Gamepad.h
index c8d98d641690a..92cc6aaebf537 100644
--- a/dom/gamepad/Gamepad.h
+++ b/dom/gamepad/Gamepad.h
@@ -25,6 +25,8 @@
 namespace mozilla {
 namespace dom {
 
+class GamepadHapticActuator;
+
 // Per spec:
 // https://dvcs.w3.org/hg/gamepad/raw-file/default/gamepad.html#remapping
 const int kStandardGamepadButtons = 17;
diff --git a/dom/gamepad/GamepadPose.h b/dom/gamepad/GamepadPose.h
index d00129e48200d..097cbb7058f58 100644
--- a/dom/gamepad/GamepadPose.h
+++ b/dom/gamepad/GamepadPose.h
@@ -10,6 +10,7 @@
 #include "mozilla/TypedEnumBits.h"
 #include "mozilla/dom/Pose.h"
 #include "mozilla/dom/GamepadPoseState.h"
+#include "nsCOMPtr.h"
 
 namespace mozilla {
 namespace dom {
diff --git a/dom/l10n/L10nMutations.h b/dom/l10n/L10nMutations.h
index 90bf079e0c821..47c11a3a9d014 100644
--- a/dom/l10n/L10nMutations.h
+++ b/dom/l10n/L10nMutations.h
@@ -7,6 +7,8 @@
 #ifndef mozilla_dom_l10n_L10nMutations_h
 #define mozilla_dom_l10n_L10nMutations_h
 
+#include "nsCycleCollectionParticipant.h"
+#include "nsHashKeys.h"
 #include "nsRefreshObservers.h"
 #include "nsStubMutationObserver.h"
 #include "nsTHashSet.h"
diff --git a/dom/media/AudioChannelFormat.h b/dom/media/AudioChannelFormat.h
index 78a2d902a6de3..f4adc6e9acc7b 100644
--- a/dom/media/AudioChannelFormat.h
+++ b/dom/media/AudioChannelFormat.h
@@ -11,6 +11,7 @@
 #include "mozilla/PodOperations.h"
 #include "nsTArrayForwardDeclare.h"
 #include "AudioSampleFormat.h"
+#include "mozilla/PodOperations.h"
 #include "nsTArray.h"
 
 namespace mozilla {
diff --git a/dom/media/platforms/SimpleMap.h b/dom/media/platforms/SimpleMap.h
index d37057e1aa597..415e8542c9f33 100644
--- a/dom/media/platforms/SimpleMap.h
+++ b/dom/media/platforms/SimpleMap.h
@@ -5,6 +5,7 @@
 #ifndef mozilla_SimpleMap_h
 #define mozilla_SimpleMap_h
 
+#include "mozilla/Mutex.h"
 #include "nsTArray.h"
 
 #include <utility>
diff --git a/dom/media/systemservices/video_engine/desktop_capture_impl.h b/dom/media/systemservices/video_engine/desktop_capture_impl.h
index 75995564e5438..137281596e667 100644
--- a/dom/media/systemservices/video_engine/desktop_capture_impl.h
+++ b/dom/media/systemservices/video_engine/desktop_capture_impl.h
@@ -20,6 +20,7 @@
 
 #include "api/video/video_frame.h"
 #include "common_video/libyuv/include/webrtc_libyuv.h"
+#include "modules/video_capture/video_capture.h"
 #include "modules/video_capture/video_capture_config.h"
 #include "modules/desktop_capture/shared_memory.h"
 #include "modules/desktop_capture/desktop_device_info.h"
diff --git a/dom/media/webm/NesteggPacketHolder.h b/dom/media/webm/NesteggPacketHolder.h
index b9abf6c68bf99..7c74f752d35f8 100644
--- a/dom/media/webm/NesteggPacketHolder.h
+++ b/dom/media/webm/NesteggPacketHolder.h
@@ -6,6 +6,7 @@
 #if !defined(NesteggPacketHolder_h_)
 #  define NesteggPacketHolder_h_
 
+#  include <deque>
 #  include <stdint.h>
 #  include "nsAutoRef.h"
 #  include "nestegg/nestegg.h"
diff --git a/dom/media/webrtc/SineWaveGenerator.h b/dom/media/webrtc/SineWaveGenerator.h
index 6053b1c5b1bd4..73bab53f19a14 100644
--- a/dom/media/webrtc/SineWaveGenerator.h
+++ b/dom/media/webrtc/SineWaveGenerator.h
@@ -6,6 +6,7 @@
 #define SINEWAVEGENERATOR_H_
 
 #include "MediaSegment.h"
+#include "prtime.h"
 
 namespace mozilla {
 
diff --git a/dom/media/webrtc/libwebrtcglue/GmpVideoCodec.h b/dom/media/webrtc/libwebrtcglue/GmpVideoCodec.h
index 318a891d06788..af4dd9f7a4004 100644
--- a/dom/media/webrtc/libwebrtcglue/GmpVideoCodec.h
+++ b/dom/media/webrtc/libwebrtcglue/GmpVideoCodec.h
@@ -5,9 +5,11 @@
 #ifndef GMPVIDEOCODEC_H_
 #define GMPVIDEOCODEC_H_
 
-#include "MediaConduitInterface.h"
-
 namespace mozilla {
+
+class WebrtcVideoDecoder;
+class WebrtcVideoEncoder;
+
 class GmpVideoCodec {
  public:
   static WebrtcVideoEncoder* CreateEncoder();
diff --git a/dom/payments/PaymentRequestUtils.h b/dom/payments/PaymentRequestUtils.h
index 9ec4bdbfcefd3..98db83330831c 100644
--- a/dom/payments/PaymentRequestUtils.h
+++ b/dom/payments/PaymentRequestUtils.h
@@ -7,6 +7,7 @@
 #ifndef mozilla_dom_PaymentRequestUtils_h
 #define mozilla_dom_PaymentRequestUtils_h
 
+#include "js/TypeDecls.h"
 #include "nsTArray.h"
 
 namespace mozilla {
diff --git a/dom/security/nsHTTPSOnlyStreamListener.h b/dom/security/nsHTTPSOnlyStreamListener.h
index 85845878205b8..a2ab4711e3b6d 100644
--- a/dom/security/nsHTTPSOnlyStreamListener.h
+++ b/dom/security/nsHTTPSOnlyStreamListener.h
@@ -11,6 +11,8 @@
 #include "nsCOMPtr.h"
 #include "nsIStreamListener.h"
 
+class nsILoadInfo;
+
 /**
  * This event listener gets registered for requests that have been upgraded
  * using the HTTPS-only mode to log failed upgrades to the console.
diff --git a/dom/webauthn/WebAuthnManager.h b/dom/webauthn/WebAuthnManager.h
index be82c26333b43..7c8660e77473e 100644
--- a/dom/webauthn/WebAuthnManager.h
+++ b/dom/webauthn/WebAuthnManager.h
@@ -9,6 +9,7 @@
 
 #include "mozilla/Maybe.h"
 #include "mozilla/MozPromise.h"
+#include "mozilla/dom/AbortSignal.h"
 #include "mozilla/dom/PWebAuthnTransaction.h"
 #include "mozilla/dom/WebAuthnManagerBase.h"
 
diff --git a/dom/webgpu/Buffer.h b/dom/webgpu/Buffer.h
index 4b7537cc6d510..2a5a8652b257e 100644
--- a/dom/webgpu/Buffer.h
+++ b/dom/webgpu/Buffer.h
@@ -10,9 +10,17 @@
 #include "mozilla/dom/Nullable.h"
 #include "mozilla/ipc/Shmem.h"
 #include "mozilla/webgpu/WebGPUTypes.h"
+#include "nsTArray.h"
 #include "ObjectModel.h"
 
 namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+template <typename T>
+class Optional;
+}
+
 namespace ipc {
 class Shmem;
 }  // namespace ipc
diff --git a/dom/webgpu/CommandBuffer.h b/dom/webgpu/CommandBuffer.h
index e0748c29fde77..36e7e2aa6fb3b 100644
--- a/dom/webgpu/CommandBuffer.h
+++ b/dom/webgpu/CommandBuffer.h
@@ -7,6 +7,7 @@
 #define GPU_CommandBuffer_H_
 
 #include "mozilla/WeakPtr.h"
+#include "mozilla/webgpu/WebGPUTypes.h"
 #include "nsWrapperCache.h"
 #include "ObjectModel.h"
 
diff --git a/dom/webgpu/CommandEncoder.h b/dom/webgpu/CommandEncoder.h
index ca04809db6a51..bf90a2ba538f2 100644
--- a/dom/webgpu/CommandEncoder.h
+++ b/dom/webgpu/CommandEncoder.h
@@ -13,6 +13,8 @@
 #include "ObjectModel.h"
 
 namespace mozilla {
+class ErrorResult;
+
 namespace dom {
 struct GPUComputePassDescriptor;
 struct GPUTextureDataLayout;
diff --git a/dom/webgpu/ComputePassEncoder.h b/dom/webgpu/ComputePassEncoder.h
index 04828620ded1c..b674fd50aaa7c 100644
--- a/dom/webgpu/ComputePassEncoder.h
+++ b/dom/webgpu/ComputePassEncoder.h
@@ -11,6 +11,12 @@
 #include "ObjectModel.h"
 
 namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+struct GPUComputePassDescriptor;
+}
+
 namespace webgpu {
 namespace ffi {
 struct WGPUComputePass;
diff --git a/dom/webgpu/Device.h b/dom/webgpu/Device.h
index 4de7a537782c4..52e95610e6e2f 100644
--- a/dom/webgpu/Device.h
+++ b/dom/webgpu/Device.h
@@ -6,6 +6,7 @@
 #ifndef GPU_DEVICE_H_
 #define GPU_DEVICE_H_
 
+#include "ObjectModel.h"
 #include "mozilla/MozPromise.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/webgpu/WebGPUTypes.h"
diff --git a/dom/webgpu/Queue.h b/dom/webgpu/Queue.h
index c6a1362cfe53d..cc074796c0b89 100644
--- a/dom/webgpu/Queue.h
+++ b/dom/webgpu/Queue.h
@@ -9,6 +9,7 @@
 #include "nsWrapperCache.h"
 #include "ObjectModel.h"
 #include "mozilla/dom/TypedArray.h"
+#include "mozilla/webgpu/WebGPUTypes.h"
 
 namespace mozilla {
 class ErrorResult;
@@ -19,6 +20,8 @@ template <typename T>
 class Optional;
 template <typename T>
 class Sequence;
+struct GPUTextureCopyView;
+struct GPUTextureDataLayout;
 struct TextureCopyView;
 struct TextureDataLayout;
 typedef RangeEnforcedUnsignedLongSequenceOrGPUExtent3DDict GPUExtent3D;
diff --git a/dom/webgpu/RenderPassEncoder.h b/dom/webgpu/RenderPassEncoder.h
index 69e1cea19233a..dea1f2635e3d3 100644
--- a/dom/webgpu/RenderPassEncoder.h
+++ b/dom/webgpu/RenderPassEncoder.h
@@ -11,8 +11,11 @@
 #include "ObjectModel.h"
 
 namespace mozilla {
+class ErrorResult;
+
 namespace dom {
 class DoubleSequenceOrGPUColorDict;
+struct GPURenderPassDescriptor;
 template <typename T>
 class Sequence;
 namespace binding_detail {
@@ -25,9 +28,12 @@ namespace ffi {
 struct WGPURenderPass;
 }  // namespace ffi
 
+class BindGroup;
+class Buffer;
 class CommandEncoder;
 class RenderBundle;
 class RenderPipeline;
+class TextureView;
 
 struct ScopedFfiRenderTraits {
   typedef ffi::WGPURenderPass* type;
diff --git a/dom/webgpu/Sampler.h b/dom/webgpu/Sampler.h
index 512d5fe247a95..c47e60ee6ee9a 100644
--- a/dom/webgpu/Sampler.h
+++ b/dom/webgpu/Sampler.h
@@ -6,6 +6,7 @@
 #ifndef GPU_SAMPLER_H_
 #define GPU_SAMPLER_H_
 
+#include "mozilla/webgpu/WebGPUTypes.h"
 #include "nsWrapperCache.h"
 #include "ObjectModel.h"
 
diff --git a/dom/webgpu/ShaderModule.h b/dom/webgpu/ShaderModule.h
index d64fce322e574..e76331686a858 100644
--- a/dom/webgpu/ShaderModule.h
+++ b/dom/webgpu/ShaderModule.h
@@ -6,6 +6,7 @@
 #ifndef GPU_ShaderModule_H_
 #define GPU_ShaderModule_H_
 
+#include "mozilla/webgpu/WebGPUTypes.h"
 #include "nsWrapperCache.h"
 #include "ObjectModel.h"
 
diff --git a/dom/xslt/xslt/txKey.h b/dom/xslt/xslt/txKey.h
index 5bfc704d2be68..0205f24af0ecf 100644
--- a/dom/xslt/xslt/txKey.h
+++ b/dom/xslt/xslt/txKey.h
@@ -7,8 +7,9 @@
 #define txKey_h__
 
 #include "nsTHashtable.h"
-#include "txNodeSet.h"
+#include "txExpandedNameMap.h"
 #include "txList.h"
+#include "txNodeSet.h"
 #include "txXSLTPatterns.h"
 #include "txXMLUtils.h"
 
diff --git a/dom/xul/nsXULCommandDispatcher.h b/dom/xul/nsXULCommandDispatcher.h
index baf1826da9b4d..ff364067d9855 100644
--- a/dom/xul/nsXULCommandDispatcher.h
+++ b/dom/xul/nsXULCommandDispatcher.h
@@ -17,8 +17,10 @@
 #include "nsWeakReference.h"
 #include "nsString.h"
 #include "nsCycleCollectionParticipant.h"
+#include "nsTArray.h"
 #include "mozilla/RefPtr.h"
 
+class nsPIDOMWindowOuter;
 class nsPIWindowRoot;
 
 namespace mozilla {
diff --git a/gfx/2d/FilterNodeD2D1.h b/gfx/2d/FilterNodeD2D1.h
index 18d475c7e70b3..a2f6e684f9e10 100644
--- a/gfx/2d/FilterNodeD2D1.h
+++ b/gfx/2d/FilterNodeD2D1.h
@@ -10,6 +10,7 @@
 #include "2D.h"
 #include "Filters.h"
 #include <vector>
+#include <windows.h>
 #include <d2d1_1.h>
 #include <cguid.h>
 
diff --git a/gfx/2d/ssse3-scaler.h b/gfx/2d/ssse3-scaler.h
index 4496e5b5df1a5..371bc86210386 100644
--- a/gfx/2d/ssse3-scaler.h
+++ b/gfx/2d/ssse3-scaler.h
@@ -8,6 +8,7 @@
 #define MOZILLA_GFX_2D_SSSE3_SCALER_H_
 
 #include <stdbool.h>
+#include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/gfx/gl/GLBlitHelper.h b/gfx/gl/GLBlitHelper.h
index 3985627510d13..fa2d9f8b1be5c 100644
--- a/gfx/gl/GLBlitHelper.h
+++ b/gfx/gl/GLBlitHelper.h
@@ -7,21 +7,28 @@
 #ifndef GLBLITHELPER_H_
 #define GLBLITHELPER_H_
 
-#include "GLContextTypes.h"
+#include <cstdint>
+#include <map>
 #include "GLConsts.h"
-#include "mozilla/gfx/Rect.h"
+#include "GLContextTypes.h"
+#include "GLTypes.h"
 #include "nsSize.h"
+#include "nsString.h"
 #include "nsTString.h"
 #include "mozilla/ipc/IPCTypes.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
 #include "mozilla/gfx/Point.h"
-#include "../layers/ImageTypes.h"
-#include "nsStringFwd.h"
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/gfx/Types.h"
 
 #include <map>
 
 #ifdef XP_WIN
 #  include <windows.h>
+#  include "mozilla/RefPtr.h"
+#  include "mozilla/ipc/IPCTypes.h"
+struct ID3D11Device;
 struct ID3D11Texture2D;
 #endif
 
@@ -32,16 +39,25 @@ class MacIOSurface;
 namespace mozilla {
 
 namespace layers {
-class D3D11ShareHandleImage;
-class D3D11YCbCrImage;
 class Image;
 class GPUVideoImage;
 class PlanarYCbCrImage;
-class SurfaceTextureImage;
-class MacIOSurfaceImage;
 class SurfaceDescriptor;
+
+#ifdef XP_WIN
+class D3D11ShareHandleImage;
+class D3D11YCbCrImage;
 class SurfaceDescriptorD3D10;
 class SurfaceDescriptorDXGIYCbCr;
+#endif
+
+#ifdef MOZ_WIDGET_ANDROID
+class SurfaceTextureImage;
+#endif
+
+#ifdef XP_MACOSX
+class MacIOSurfaceImage;
+#endif
 }  // namespace layers
 
 namespace gl {
diff --git a/gfx/gl/GLXLibrary.h b/gfx/gl/GLXLibrary.h
index a694af186259f..8aa20b679c9cf 100644
--- a/gfx/gl/GLXLibrary.h
+++ b/gfx/gl/GLXLibrary.h
@@ -7,6 +7,7 @@
 #define GFX_GLXLIBRARY_H
 
 #include "GLContextTypes.h"
+#include "mozilla/Assertions.h"
 #include "prlink.h"
 typedef realGLboolean GLboolean;
 
diff --git a/gfx/layers/composite/PaintCounter.h b/gfx/layers/composite/PaintCounter.h
index 084330c998f95..f4a2d42ae4540 100644
--- a/gfx/layers/composite/PaintCounter.h
+++ b/gfx/layers/composite/PaintCounter.h
@@ -7,19 +7,24 @@
 #ifndef mozilla_layers_PaintCounter_h_
 #define mozilla_layers_PaintCounter_h_
 
-#include <map>  // for std::map
+#include <memory>
 #include "mozilla/Maybe.h"
 #include "mozilla/RefPtr.h"     // for already_AddRefed, RefCounted
 #include "mozilla/TimeStamp.h"  // for TimeStamp, TimeDuration
-#include "skia/include/core/SkCanvas.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/gfx/Types.h"
+#include "nsISupports.h"
+
+class SkCanvas;
 
 namespace mozilla {
 namespace layers {
 
 class Compositor;
-
-using namespace mozilla::gfx;
-using namespace mozilla::gl;
+class DataTextureSource;
+struct TexturedEffect;
 
 // Keeps track and paints how long a full invalidation paint takes to rasterize
 // and composite.
@@ -30,21 +35,21 @@ class PaintCounter {
   PaintCounter();
   void Draw(Compositor* aCompositor, TimeDuration aPaintTime,
             TimeDuration aCompositeTime);
-  static IntRect GetPaintRect() { return PaintCounter::mRect; }
+  static gfx::IntRect GetPaintRect() { return PaintCounter::mRect; }
 
  private:
   virtual ~PaintCounter();
 
-  SurfaceFormat mFormat;
+  gfx::SurfaceFormat mFormat;
   std::unique_ptr<SkCanvas> mCanvas;
-  IntSize mSize;
+  gfx::IntSize mSize;
   int mStride;
 
-  RefPtr<DataSourceSurface> mSurface;
+  RefPtr<gfx::DataSourceSurface> mSurface;
   RefPtr<DataTextureSource> mTextureSource;
   RefPtr<TexturedEffect> mTexturedEffect;
-  Maybe<DataSourceSurface::ScopedMap> mMap;
-  static IntRect mRect;
+  Maybe<gfx::DataSourceSurface::ScopedMap> mMap;
+  static gfx::IntRect mRect;
 };
 
 }  // namespace layers
diff --git a/gfx/src/RegionBuilder.h b/gfx/src/RegionBuilder.h
index c866f8fcf6762..4913c4361995c 100644
--- a/gfx/src/RegionBuilder.h
+++ b/gfx/src/RegionBuilder.h
@@ -7,7 +7,8 @@
 #ifndef RegionBuilder_h__
 #define RegionBuilder_h__
 
-#include <nsTArray.h>
+#include "nsTArray.h"
+#include "pixman.h"
 
 template <typename RegionType>
 class RegionBuilder {
diff --git a/gfx/vr/service/OculusSession.h b/gfx/vr/service/OculusSession.h
index e1feeb205298d..0ab70e1817f60 100644
--- a/gfx/vr/service/OculusSession.h
+++ b/gfx/vr/service/OculusSession.h
@@ -9,8 +9,9 @@
 
 #include "VRSession.h"
 
-#include "mozilla/gfx/2D.h"
 #include "moz_external_vr.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/gfx/2D.h"
 #include "nsTArray.h"
 #include "oculus/ovr_capi_dynamic.h"
 #include "prlink.h"
diff --git a/image/ImageMetadata.h b/image/ImageMetadata.h
index 33e95d850f44c..36dc0f3b48304 100644
--- a/image/ImageMetadata.h
+++ b/image/ImageMetadata.h
@@ -8,11 +8,14 @@
 #define mozilla_image_ImageMetadata_h
 
 #include <stdint.h>
+#include <utility>
+#include "FrameTimeout.h"
+#include "Orientation.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/Rect.h"
 #include "nsSize.h"
 #include "nsTArray.h"
-#include "Orientation.h"
-#include "FrameTimeout.h"
 
 namespace mozilla {
 namespace image {
diff --git a/layout/generic/AnonymousContentKey.h b/layout/generic/AnonymousContentKey.h
index 4246146eb34e9..cff17453b179f 100644
--- a/layout/generic/AnonymousContentKey.h
+++ b/layout/generic/AnonymousContentKey.h
@@ -11,6 +11,7 @@
 
 #include "mozilla/TypedEnumBits.h"
 #include <stdint.h>
+#include "X11UndefineNone.h"
 
 namespace mozilla {
 
diff --git a/layout/generic/nsBulletFrame.h b/layout/generic/nsBulletFrame.h
index 382d9057bf998..ffb95003cfc59 100644
--- a/layout/generic/nsBulletFrame.h
+++ b/layout/generic/nsBulletFrame.h
@@ -14,6 +14,7 @@
 
 class imgIContainer;
 class nsBulletFrame;
+class nsFontMetrics;
 class BulletRenderer;
 class nsFontMetrics;
 
diff --git a/layout/generic/nsIAnonymousContentCreator.h b/layout/generic/nsIAnonymousContentCreator.h
index 2d27e4455f587..344d9f0096c68 100644
--- a/layout/generic/nsIAnonymousContentCreator.h
+++ b/layout/generic/nsIAnonymousContentCreator.h
@@ -16,6 +16,7 @@
 
 #include "nsQueryFrame.h"
 #include "nsTArrayForwardDeclare.h"
+#include "X11UndefineNone.h"
 
 class nsIContent;
 
diff --git a/layout/style/ServoTypes.h b/layout/style/ServoTypes.h
index 3d532bd32e62d..c18b5f3da5760 100644
--- a/layout/style/ServoTypes.h
+++ b/layout/style/ServoTypes.h
@@ -12,6 +12,7 @@
 #include "mozilla/RefPtr.h"
 #include "mozilla/TypedEnumBits.h"
 #include "nsCoord.h"
+#include "X11UndefineNone.h"
 
 struct RawServoFontFaceRule;
 
diff --git a/media/webrtc/signaling/gtest/MockCall.h b/media/webrtc/signaling/gtest/MockCall.h
index 9f4abcb35d01f..0ce3c9ac8aed8 100644
--- a/media/webrtc/signaling/gtest/MockCall.h
+++ b/media/webrtc/signaling/gtest/MockCall.h
@@ -5,6 +5,7 @@
 #ifndef MOCK_CALL_H_
 #define MOCK_CALL_H_
 
+#include "mozilla/Assertions.h"
 #include <webrtc/api/call/audio_sink.h>
 #include <webrtc/call/call.h>
 
diff --git a/memory/build/mozjemalloc_types.h b/memory/build/mozjemalloc_types.h
index f6eb5bc0274ce..14c2641fff7f0 100644
--- a/memory/build/mozjemalloc_types.h
+++ b/memory/build/mozjemalloc_types.h
@@ -36,6 +36,8 @@
 #ifndef _JEMALLOC_TYPES_H_
 #define _JEMALLOC_TYPES_H_
 
+#include <stdint.h>
+
 // grab size_t
 #ifdef _MSC_VER
 #  include <crtdefs.h>
diff --git a/modules/libmar/src/mar.h b/modules/libmar/src/mar.h
index 4c3ae92ab13f6..4f9ae487e7a2c 100644
--- a/modules/libmar/src/mar.h
+++ b/modules/libmar/src/mar.h
@@ -9,6 +9,7 @@
 
 #include <assert.h>  // for C11 static_assert
 #include <stdint.h>
+#include <stdio.h>
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/mozglue/android/Ashmem.h b/mozglue/android/Ashmem.h
index 9779f71ba0f3c..3307761e32903 100644
--- a/mozglue/android/Ashmem.h
+++ b/mozglue/android/Ashmem.h
@@ -6,6 +6,7 @@
 #define Ashmem_h__
 
 #include <linux/ashmem.h>
+#include "mozilla/Types.h"
 
 namespace mozilla {
 namespace android {
diff --git a/mozglue/linker/Elfxx.h b/mozglue/linker/Elfxx.h
index a8712802138c7..4390d2ccc7e49 100644
--- a/mozglue/linker/Elfxx.h
+++ b/mozglue/linker/Elfxx.h
@@ -5,6 +5,8 @@
 #ifndef Elfxx_h
 #define Elfxx_h
 
+#include "Utils.h"
+
 /**
  * Android system headers have two different elf.h file. The one under linux/
  * is the most complete on older Android API versions without unified headers.
diff --git a/mozglue/misc/PlatformMutex.h b/mozglue/misc/PlatformMutex.h
index 704bf60e412a9..1d135b571142d 100644
--- a/mozglue/misc/PlatformMutex.h
+++ b/mozglue/misc/PlatformMutex.h
@@ -10,6 +10,7 @@
 #include <utility>
 
 #include "mozilla/Attributes.h"
+#include "mozilla/Types.h"
 
 #if !defined(XP_WIN)
 #  include <pthread.h>
diff --git a/netwerk/base/LoadTainting.h b/netwerk/base/LoadTainting.h
index e01d5cd6a37ab..aec60ef4d3f46 100644
--- a/netwerk/base/LoadTainting.h
+++ b/netwerk/base/LoadTainting.h
@@ -7,6 +7,8 @@
 #ifndef mozilla_LoadTainting_h
 #define mozilla_LoadTainting_h
 
+#include <stdint.h>
+
 namespace mozilla {
 
 // Define an enumeration to reflect the concept of response tainting from the
diff --git a/netwerk/base/nsASocketHandler.h b/netwerk/base/nsASocketHandler.h
index 95c847cdb064e..73b12201c7cea 100644
--- a/netwerk/base/nsASocketHandler.h
+++ b/netwerk/base/nsASocketHandler.h
@@ -5,6 +5,10 @@
 #ifndef nsASocketHandler_h__
 #define nsASocketHandler_h__
 
+#include "nsError.h"
+#include "nsISupports.h"
+#include "prio.h"
+
 // socket handler used by nsISocketTransportService.
 // methods are only called on the socket thread.
 
diff --git a/netwerk/base/nsUDPSocket.h b/netwerk/base/nsUDPSocket.h
index 898d59db8be59..dfc8987d89a02 100644
--- a/netwerk/base/nsUDPSocket.h
+++ b/netwerk/base/nsUDPSocket.h
@@ -10,6 +10,7 @@
 #include "mozilla/Mutex.h"
 #include "mozilla/net/DNS.h"
 #include "nsIOutputStream.h"
+#include "nsASocketHandler.h"
 #include "nsCycleCollectionParticipant.h"
 
 //-----------------------------------------------------------------------------
@@ -17,6 +18,8 @@
 namespace mozilla {
 namespace net {
 
+class nsSocketTransportService;
+
 class nsUDPSocket final : public nsASocketHandler, public nsIUDPSocket {
  public:
   NS_DECL_THREADSAFE_ISUPPORTS
diff --git a/netwerk/dns/DNSPacket.h b/netwerk/dns/DNSPacket.h
index d2827880a19d3..a440dfc390491 100644
--- a/netwerk/dns/DNSPacket.h
+++ b/netwerk/dns/DNSPacket.h
@@ -9,6 +9,7 @@
 #include "mozilla/Result.h"
 #include "pk11pub.h"
 #include "ScopedNSSTypes.h"
+#include "nsClassHashtable.h"
 #include "nsIDNSService.h"
 
 namespace mozilla {
diff --git a/netwerk/protocol/http/ASpdySession.h b/netwerk/protocol/http/ASpdySession.h
index ab2dbc722b8c0..1a7e4c749653e 100644
--- a/netwerk/protocol/http/ASpdySession.h
+++ b/netwerk/protocol/http/ASpdySession.h
@@ -9,6 +9,7 @@
 
 #include "nsAHttpTransaction.h"
 #include "prinrval.h"
+#include "nsHttp.h"
 #include "nsString.h"
 
 class nsISocketTransport;
diff --git a/netwerk/protocol/http/nsHttpChannelAuthProvider.cpp b/netwerk/protocol/http/nsHttpChannelAuthProvider.cpp
index df3fbbc6a63b5..6516ffd080120 100644
--- a/netwerk/protocol/http/nsHttpChannelAuthProvider.cpp
+++ b/netwerk/protocol/http/nsHttpChannelAuthProvider.cpp
@@ -27,6 +27,7 @@
 #include "nsIHttpAuthenticableChannel.h"
 #include "nsIURI.h"
 #include "nsContentUtils.h"
+#include "nsHttp.h"
 #include "nsHttpBasicAuth.h"
 #include "nsHttpDigestAuth.h"
 #include "nsHttpNegotiateAuth.h"
diff --git a/netwerk/protocol/http/nsHttpChannelAuthProvider.h b/netwerk/protocol/http/nsHttpChannelAuthProvider.h
index 4bff58ae96804..6699a2486f998 100644
--- a/netwerk/protocol/http/nsHttpChannelAuthProvider.h
+++ b/netwerk/protocol/http/nsHttpChannelAuthProvider.h
@@ -25,6 +25,7 @@ namespace mozilla {
 namespace net {
 
 class nsHttpHandler;
+struct nsHttpAtom;
 
 class nsHttpChannelAuthProvider final : public nsIHttpChannelAuthProvider,
                                         public nsIAuthPromptCallback,
diff --git a/netwerk/system/mac/nsNetworkLinkService.h b/netwerk/system/mac/nsNetworkLinkService.h
index b4e3b62419d34..1bd484cb6aef3 100644
--- a/netwerk/system/mac/nsNetworkLinkService.h
+++ b/netwerk/system/mac/nsNetworkLinkService.h
@@ -8,9 +8,11 @@
 #include "nsINetworkLinkService.h"
 #include "nsIObserver.h"
 #include "nsITimer.h"
+#include "nsString.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/SHA1.h"
 
+#include <netinet/in.h>
 #include <SystemConfiguration/SCNetworkReachability.h>
 #include <SystemConfiguration/SystemConfiguration.h>
 
diff --git a/netwerk/system/win32/nsNotifyAddrListener.cpp b/netwerk/system/win32/nsNotifyAddrListener.cpp
index 6228d97f06f1e..27c444e7d2059 100644
--- a/netwerk/system/win32/nsNotifyAddrListener.cpp
+++ b/netwerk/system/win32/nsNotifyAddrListener.cpp
@@ -39,6 +39,7 @@
 #include "nsPrintfCString.h"
 #include "mozilla/Services.h"
 #include "nsCRT.h"
+#include "nsThreadPool.h"
 #include "mozilla/StaticPrefs_network.h"
 #include "mozilla/SHA1.h"
 #include "mozilla/Base64.h"
diff --git a/netwerk/system/win32/nsNotifyAddrListener.h b/netwerk/system/win32/nsNotifyAddrListener.h
index 4fe203e820595..3406dd3b94ac3 100644
--- a/netwerk/system/win32/nsNotifyAddrListener.h
+++ b/netwerk/system/win32/nsNotifyAddrListener.h
@@ -12,6 +12,8 @@
 #include "nsINetworkLinkService.h"
 #include "nsIRunnable.h"
 #include "nsIObserver.h"
+#include "nsString.h"
+#include "nsTArray.h"
 #include "nsThreadUtils.h"
 #include "nsThreadPool.h"
 #include "nsCOMPtr.h"
@@ -21,6 +23,8 @@
 #include "mozilla/SHA1.h"
 #include "mozilla/net/DNS.h"
 
+class nsIThreadPool;
+
 class nsNotifyAddrListener : public nsINetworkLinkService,
                              public nsIRunnable,
                              public nsIObserver {
diff --git a/parser/expat/lib/expat.h b/parser/expat/lib/expat.h
index 9e1dfc42a06af..5fe365e486435 100644
--- a/parser/expat/lib/expat.h
+++ b/parser/expat/lib/expat.h
@@ -15,6 +15,7 @@
 #endif
 
 #include <stdlib.h>
+#include "expat_config.h"
 #include "expat_external.h"
 
 #ifdef __cplusplus
diff --git a/parser/html/nsAHtml5TreeBuilderState.h b/parser/html/nsAHtml5TreeBuilderState.h
index 1dd211f565e36..0de332b93cecd 100644
--- a/parser/html/nsAHtml5TreeBuilderState.h
+++ b/parser/html/nsAHtml5TreeBuilderState.h
@@ -5,8 +5,13 @@
 #ifndef nsAHtml5TreeBuilderState_h
 #define nsAHtml5TreeBuilderState_h
 
+#include <cstdint>
 #include "nsIContentHandle.h"
 
+template <class T, class L>
+class jArray;
+class nsHtml5StackNode;
+
 /**
  * Interface for exposing the internal state of the HTML5 tree builder.
  * For more documentation, please see
diff --git a/parser/html/nsAHtml5TreeOpSink.h b/parser/html/nsAHtml5TreeOpSink.h
index f932bc6648040..bdcec970c5ac9 100644
--- a/parser/html/nsAHtml5TreeOpSink.h
+++ b/parser/html/nsAHtml5TreeOpSink.h
@@ -5,6 +5,10 @@
 #ifndef nsAHtml5TreeOpSink_h
 #define nsAHtml5TreeOpSink_h
 
+#include "nsTArrayForwardDeclare.h"
+
+class nsHtml5TreeOperation;
+
 /**
  * The purpose of this interface is to connect a tree op executor
  * (main-thread case), a tree op stage (non-speculative off-the-main-thread
diff --git a/parser/html/nsHtml5MetaScanner.h b/parser/html/nsHtml5MetaScanner.h
index d64caa92af122..bb4c7ad0fa8f4 100644
--- a/parser/html/nsHtml5MetaScanner.h
+++ b/parser/html/nsHtml5MetaScanner.h
@@ -29,21 +29,21 @@
 #ifndef nsHtml5MetaScanner_h
 #define nsHtml5MetaScanner_h
 
-#include "nsAtom.h"
-#include "nsHtml5AtomTable.h"
-#include "nsHtml5String.h"
-#include "nsNameSpaceManager.h"
-#include "nsIContent.h"
-#include "nsTraceRefcnt.h"
 #include "jArray.h"
-#include "nsHtml5ArrayCopy.h"
 #include "nsAHtml5TreeBuilderState.h"
+#include "nsAtom.h"
 #include "nsGkAtoms.h"
+#include "nsHtml5ArrayCopy.h"
+#include "nsHtml5AtomTable.h"
 #include "nsHtml5ByteReadable.h"
+#include "nsHtml5ContentCreatorFunction.h"
 #include "nsHtml5Macros.h"
-#include "nsIContentHandle.h"
 #include "nsHtml5Portability.h"
-#include "nsHtml5ContentCreatorFunction.h"
+#include "nsHtml5String.h"
+#include "nsIContent.h"
+#include "nsIContentHandle.h"
+#include "nsNameSpaceManager.h"
+#include "nsTraceRefcnt.h"
 
 class nsHtml5StreamParser;
 
diff --git a/parser/html/nsHtml5StackNode.h b/parser/html/nsHtml5StackNode.h
index 3718e81712534..3efe1f3e6830f 100644
--- a/parser/html/nsHtml5StackNode.h
+++ b/parser/html/nsHtml5StackNode.h
@@ -48,6 +48,7 @@
 class nsHtml5StreamParser;
 
 class nsHtml5AttributeName;
+class nsHtml5HtmlAttributes;
 class nsHtml5ElementName;
 class nsHtml5Tokenizer;
 class nsHtml5TreeBuilder;
diff --git a/parser/htmlparser/nsHTMLTags.h b/parser/htmlparser/nsHTMLTags.h
index 7423d52e49d42..eb7e3aaa25505 100644
--- a/parser/htmlparser/nsHTMLTags.h
+++ b/parser/htmlparser/nsHTMLTags.h
@@ -6,6 +6,7 @@
 #ifndef nsHTMLTags_h___
 #define nsHTMLTags_h___
 
+#include "nsAtom.h"
 #include "nsString.h"
 #include "nsTHashMap.h"
 #include "nsHashKeys.h"
diff --git a/security/apps/AppTrustDomain.h b/security/apps/AppTrustDomain.h
index d2651d11cae56..41b01e7ee43f2 100644
--- a/security/apps/AppTrustDomain.h
+++ b/security/apps/AppTrustDomain.h
@@ -9,8 +9,10 @@
 
 #include "mozilla/Span.h"
 #include "mozpkix/pkixtypes.h"
+#include "nsCOMPtr.h"
 #include "nsDebug.h"
 #include "nsICertStorage.h"
+#include "nsIX509CertDB.h"
 #include "nsTArray.h"
 
 namespace mozilla {
diff --git a/storage/mozIStorageService.idl b/storage/mozIStorageService.idl
index 57368fd08e992..f6c1af5ddc90c 100644
--- a/storage/mozIStorageService.idl
+++ b/storage/mozIStorageService.idl
@@ -5,6 +5,12 @@
 
 #include "nsISupports.idl"
 
+%{C++
+
+#include "nsLiteralString.h"
+
+%}
+
 interface mozIStorageConnection;
 interface nsIFile;
 interface nsIFileURL;
diff --git a/storage/mozStorageHelper.h b/storage/mozStorageHelper.h
index b4987e27ee52b..35ee54faa3779 100644
--- a/storage/mozStorageHelper.h
+++ b/storage/mozStorageHelper.h
@@ -15,6 +15,8 @@
 #include "mozIStorageConnection.h"
 #include "mozIStorageStatement.h"
 #include "mozIStoragePendingStatement.h"
+#include "mozilla/DebugOnly.h"
+#include "nsCOMPtr.h"
 #include "nsError.h"
 
 /**
diff --git a/toolkit/components/ctypes/tests/jsctypes-test-finalizer.h b/toolkit/components/ctypes/tests/jsctypes-test-finalizer.h
index 45888dd2b7be2..8ef4e110eda5c 100644
--- a/toolkit/components/ctypes/tests/jsctypes-test-finalizer.h
+++ b/toolkit/components/ctypes/tests/jsctypes-test-finalizer.h
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "jsctypes-test.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Types.h"
 
diff --git a/toolkit/components/extensions/webrequest/WebRequestService.h b/toolkit/components/extensions/webrequest/WebRequestService.h
index e75d59ceadafb..b9635861697ee 100644
--- a/toolkit/components/extensions/webrequest/WebRequestService.h
+++ b/toolkit/components/extensions/webrequest/WebRequestService.h
@@ -28,6 +28,8 @@ class ContentParent;
 
 namespace extensions {
 
+class ChannelWrapper;
+
 class WebRequestChannelEntry final {
  public:
   ~WebRequestChannelEntry();
diff --git a/toolkit/components/maintenanceservice/maintenanceservice.h b/toolkit/components/maintenanceservice/maintenanceservice.h
index 7f04c7c743d9d..596b2b44ee7f2 100644
--- a/toolkit/components/maintenanceservice/maintenanceservice.h
+++ b/toolkit/components/maintenanceservice/maintenanceservice.h
@@ -2,8 +2,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#ifndef TOOLKIT_COMPONENTS_MAINTENANCESERVICE_MAINTENANCESERVICE_H_
+#define TOOLKIT_COMPONENTS_MAINTENANCESERVICE_MAINTENANCESERVICE_H_
+
+#include <windows.h>
+
 void WINAPI SvcMain(DWORD dwArgc, LPWSTR* lpszArgv);
 void SvcInit(DWORD dwArgc, LPWSTR* lpszArgv);
 void WINAPI SvcCtrlHandler(DWORD dwCtrl);
 void ReportSvcStatus(DWORD dwCurrentState, DWORD dwWin32ExitCode,
                      DWORD dwWaitHint);
+
+#endif  // TOOLKIT_COMPONENTS_MAINTENANCESERVICE_MAINTENANCESERVICE_H_
diff --git a/toolkit/components/printingui/ipc/PrintProgressDialogChild.h b/toolkit/components/printingui/ipc/PrintProgressDialogChild.h
index 74899c07f9b18..0a28efb292ceb 100644
--- a/toolkit/components/printingui/ipc/PrintProgressDialogChild.h
+++ b/toolkit/components/printingui/ipc/PrintProgressDialogChild.h
@@ -6,6 +6,7 @@
 #define mozilla_embedding_PrintProgressDialogChild_h
 
 #include "mozilla/embedding/PPrintProgressDialogChild.h"
+#include "nsIPrintProgressParams.h"
 #include "nsIPrintSettings.h"
 #include "nsIWebProgressListener.h"
 
diff --git a/toolkit/components/remote/WinRemoteMessage.h b/toolkit/components/remote/WinRemoteMessage.h
index ba6a0836b43bb..c38eff7458236 100644
--- a/toolkit/components/remote/WinRemoteMessage.h
+++ b/toolkit/components/remote/WinRemoteMessage.h
@@ -10,6 +10,7 @@
 
 #include "nsICommandLineRunner.h"
 #include "nsCOMPtr.h"
+#include "nsString.h"
 
 // This version defines the format of COPYDATASTRUCT::lpData in a message of
 // WM_COPYDATA.
diff --git a/toolkit/components/resistfingerprinting/RelativeTimeline.h b/toolkit/components/resistfingerprinting/RelativeTimeline.h
index 8d8aaf0b5d9e8..bf23de904d8ff 100644
--- a/toolkit/components/resistfingerprinting/RelativeTimeline.h
+++ b/toolkit/components/resistfingerprinting/RelativeTimeline.h
@@ -6,6 +6,8 @@
 #ifndef __RelativeTimeline_h__
 #define __RelativeTimeline_h__
 
+#include <cstdint>
+
 namespace mozilla {
 
 class RelativeTimeline {
diff --git a/toolkit/components/sessionstore/SessionStoreListener.h b/toolkit/components/sessionstore/SessionStoreListener.h
index 6420bb52278b8..ea803865e17cb 100644
--- a/toolkit/components/sessionstore/SessionStoreListener.h
+++ b/toolkit/components/sessionstore/SessionStoreListener.h
@@ -7,10 +7,12 @@
 #ifndef mozilla_dom_SessionStoreListener_h
 #define mozilla_dom_SessionStoreListener_h
 
+#include "SessionStoreData.h"
 #include "nsIDOMEventListener.h"
+#include "nsIObserver.h"
 #include "nsIPrivacyTransitionObserver.h"
 #include "nsIWebProgressListener.h"
-#include "SessionStoreData.h"
+#include "nsWeakReference.h"
 
 class nsITimer;
 
diff --git a/toolkit/components/telemetry/build_scripts/gen_event_data.py b/toolkit/components/telemetry/build_scripts/gen_event_data.py
index d5c870494de8e..682107a7ef5f4 100644
--- a/toolkit/components/telemetry/build_scripts/gen_event_data.py
+++ b/toolkit/components/telemetry/build_scripts/gen_event_data.py
@@ -32,6 +32,7 @@
 #ifndef mozilla_TelemetryEventData_h
 #define mozilla_TelemetryEventData_h
 #include "core/EventInfo.h"
+#include "nsITelemetry.h"
 namespace {
 """
 
diff --git a/toolkit/components/telemetry/build_scripts/gen_scalar_data.py b/toolkit/components/telemetry/build_scripts/gen_scalar_data.py
index ef0154015fd3c..8844f6c56207d 100644
--- a/toolkit/components/telemetry/build_scripts/gen_scalar_data.py
+++ b/toolkit/components/telemetry/build_scripts/gen_scalar_data.py
@@ -32,6 +32,7 @@
 #ifndef mozilla_TelemetryScalarData_h
 #define mozilla_TelemetryScalarData_h
 #include "core/ScalarInfo.h"
+#include "nsITelemetry.h"
 namespace {
 """
 
diff --git a/toolkit/components/telemetry/core/TelemetryUserInteraction.h b/toolkit/components/telemetry/core/TelemetryUserInteraction.h
index ea03533ec350c..2b12a5f275dc5 100644
--- a/toolkit/components/telemetry/core/TelemetryUserInteraction.h
+++ b/toolkit/components/telemetry/core/TelemetryUserInteraction.h
@@ -6,6 +6,8 @@
 #ifndef TelemetryUserInteraction_h__
 #define TelemetryUserInteraction_h__
 
+#include "nsStringFwd.h"
+
 namespace TelemetryUserInteraction {
 
 void InitializeGlobalState(bool canRecordBase, bool canRecordExtended);
diff --git a/toolkit/mozapps/update/common/certificatecheck.h b/toolkit/mozapps/update/common/certificatecheck.h
index edb8ddb095aeb..af9f8456dfd43 100644
--- a/toolkit/mozapps/update/common/certificatecheck.h
+++ b/toolkit/mozapps/update/common/certificatecheck.h
@@ -5,6 +5,7 @@
 #ifndef _CERTIFICATECHECK_H_
 #define _CERTIFICATECHECK_H_
 
+#include <windows.h>
 #include <wincrypt.h>
 
 struct CertificateCheckInfo {
diff --git a/toolkit/mozapps/update/common/pathhash.h b/toolkit/mozapps/update/common/pathhash.h
index 26a182a4117fe..17f08ae95e4b2 100644
--- a/toolkit/mozapps/update/common/pathhash.h
+++ b/toolkit/mozapps/update/common/pathhash.h
@@ -5,6 +5,8 @@
 #ifndef _PATHHASH_H_
 #define _PATHHASH_H_
 
+#include <windows.h>
+
 /**
  * Converts a file path into a unique registry location for cert storage
  *
diff --git a/toolkit/mozapps/update/common/uachelper.h b/toolkit/mozapps/update/common/uachelper.h
index e9f52157879df..c9915981a05e6 100644
--- a/toolkit/mozapps/update/common/uachelper.h
+++ b/toolkit/mozapps/update/common/uachelper.h
@@ -5,6 +5,8 @@
 #ifndef _UACHELPER_H_
 #define _UACHELPER_H_
 
+#include <windows.h>
+
 class UACHelper {
  public:
   static HANDLE OpenUserToken(DWORD sessionID);
diff --git a/toolkit/mozapps/update/updater/archivereader.h b/toolkit/mozapps/update/updater/archivereader.h
index be826aa177c0a..1f18327f1d55a 100644
--- a/toolkit/mozapps/update/updater/archivereader.h
+++ b/toolkit/mozapps/update/updater/archivereader.h
@@ -11,6 +11,8 @@
 #include "mar.h"
 
 #ifdef XP_WIN
+#  include <windows.h>
+
 typedef WCHAR NS_tchar;
 #else
 typedef char NS_tchar;
diff --git a/tools/fuzzing/rust/RustFuzzingTargets.h b/tools/fuzzing/rust/RustFuzzingTargets.h
index 8f44fb277cda7..a9c1439598dcc 100644
--- a/tools/fuzzing/rust/RustFuzzingTargets.h
+++ b/tools/fuzzing/rust/RustFuzzingTargets.h
@@ -10,6 +10,9 @@
 #ifndef RustFuzzingTargets_h__
 #define RustFuzzingTargets_h__
 
+#include <stddef.h>
+#include <stdint.h>
+
 extern "C" {
 
 int fuzz_rkv_db_file(const uint8_t* raw_data, size_t size);
diff --git a/tools/fuzzing/shmem/SharedMemoryFuzzer.h b/tools/fuzzing/shmem/SharedMemoryFuzzer.h
index 51bfe5ef3e78f..bd862edf6a52a 100644
--- a/tools/fuzzing/shmem/SharedMemoryFuzzer.h
+++ b/tools/fuzzing/shmem/SharedMemoryFuzzer.h
@@ -7,6 +7,9 @@
 #ifndef mozilla_dom_SharedMemoryFuzzer_h
 #define mozilla_dom_SharedMemoryFuzzer_h
 
+#include <stddef.h>
+#include <stdint.h>
+
 namespace mozilla {
 namespace ipc {
 
diff --git a/tools/profiler/lul/LulMainInt.h b/tools/profiler/lul/LulMainInt.h
index f32c56e84f21f..c74737e27d027 100644
--- a/tools/profiler/lul/LulMainInt.h
+++ b/tools/profiler/lul/LulMainInt.h
@@ -16,6 +16,7 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/HashFunctions.h"
 #include "mozilla/HashTable.h"
+#include "mozilla/Sprintf.h"
 
 // This file provides an internal interface inside LUL.  If you are an
 // end-user of LUL, do not include it in your code.  The end-user
diff --git a/widget/cocoa/nsClipboard.h b/widget/cocoa/nsClipboard.h
index fd528162ef20d..b11ebd7cab332 100644
--- a/widget/cocoa/nsClipboard.h
+++ b/widget/cocoa/nsClipboard.h
@@ -6,6 +6,7 @@
 #ifndef nsClipboard_h_
 #define nsClipboard_h_
 
+#include "nsCOMPtr.h"
 #include "nsIClipboard.h"
 #include "nsString.h"
 #include "mozilla/Maybe.h"
diff --git a/widget/gtk/maiRedundantObjectFactory.h b/widget/gtk/maiRedundantObjectFactory.h
index 931adffb6b778..2e6d2f572ca9c 100644
--- a/widget/gtk/maiRedundantObjectFactory.h
+++ b/widget/gtk/maiRedundantObjectFactory.h
@@ -8,6 +8,9 @@
 #ifndef __MAI_REDUNDANT_OBJECT_FACTORY_H__
 #define __MAI_REDUNDANT_OBJECT_FACTORY_H__
 
+#include <atk/atk.h>
+#include <glib-object.h>
+
 G_BEGIN_DECLS
 
 typedef struct _maiRedundantObjectFactory maiRedundantObjectFactory;
diff --git a/widget/gtk/wayland/gtk-primary-selection-client-protocol.h b/widget/gtk/wayland/gtk-primary-selection-client-protocol.h
index 770c35e03f058..21cf84a6e96cd 100644
--- a/widget/gtk/wayland/gtk-primary-selection-client-protocol.h
+++ b/widget/gtk/wayland/gtk-primary-selection-client-protocol.h
@@ -5,6 +5,7 @@
 
 #include <stdint.h>
 #include <stddef.h>
+#include "mozilla/widget/mozwayland.h"
 #include "wayland-client.h"
 
 #ifdef  __cplusplus
diff --git a/widget/windows/nsDataObj.h b/widget/windows/nsDataObj.h
index d19a21860d662..e36cf93444895 100644
--- a/widget/windows/nsDataObj.h
+++ b/widget/windows/nsDataObj.h
@@ -18,6 +18,9 @@
 #include "nsIChannel.h"
 #include "nsCOMArray.h"
 #include "nsITimer.h"
+#include "nsIURI.h"
+#include "nsString.h"
+#include "nsWindowsHelpers.h"
 
 class nsICookieJarSettings;
 class nsIThread;
diff --git a/xpcom/build/XREChildData.h b/xpcom/build/XREChildData.h
index 6403b898833c6..8050fb8afc0d2 100644
--- a/xpcom/build/XREChildData.h
+++ b/xpcom/build/XREChildData.h
@@ -13,8 +13,9 @@
 #  include "mozilla/sandboxing/loggingTypes.h"
 
 namespace sandbox {
+class BrokerServices;
 class TargetServices;
-}
+}  // namespace sandbox
 #endif
 
 /**
diff --git a/xpcom/components/gen_static_components.py b/xpcom/components/gen_static_components.py
index 2c6170668871e..205602f4faa34 100644
--- a/xpcom/components/gen_static_components.py
+++ b/xpcom/components/gen_static_components.py
@@ -902,6 +902,8 @@ def replacer(match):
 #ifndef StaticComponentData_h
 #define StaticComponentData_h
 
+#include <stddef.h>
+
 namespace mozilla {
 namespace xpcom {
 
diff --git a/xpcom/ds/nsIWindowsRegKey.idl b/xpcom/ds/nsIWindowsRegKey.idl
index b260ca248ff82..197ba69c6d3ef 100644
--- a/xpcom/ds/nsIWindowsRegKey.idl
+++ b/xpcom/ds/nsIWindowsRegKey.idl
@@ -6,6 +6,10 @@
 
 #include "nsISupports.idl"
 
+%{C++
+#include <windows.h>
+%}
+
 native HKEY(HKEY);
 
 /**