Bug 1665459 - Control pre-xul skele UI registry value via prefs r=mho…

…well

This patch uses the prefs relevant to the pre-xul skeleton UI to control the
registry value. There are three prefs:

- A new pref intended to be the global toggle once all themes can be handled.
- browser.startup.blankWindow - we currently depend on the code in BrowserGlue.jsm,
  gated on this pref, which immediately specifies the width and height of the
  window and ultimately causes XUL to consume and take ownership of our pre-xul
  window. Without this, we resize to fit a small content area, and then resize
  again back to the correct size.
- extensions.activeThemeID - Given that we have hardcoded layout and colors, we
  need to ensure that we're only presenting the skeleton UI for the default theme.

We're hoping to not need to gate on any prefs other than the new pref that we're
adding, but this allows us to provide a simple direction for users who may want
to dogfood our changes in the mean time: use the default theme, ensure the
browser.startup.blankWindow pref is set, and turn our new pref on.

Differential Revision: https://phabricator.services.mozilla.com/D90884

mozglue/misc/EarlyBlankWindow.cpp

@@ -514,4 +514,24 @@ void PersistEarlyBlankWindowValues(int screenX, int screenY, int width,
   }
 }
 
+MFBT_API bool GetEarlyBlankWindowEnabled() { return sEarlyBlankWindowEnabled; }
+
+MFBT_API void SetEarlyBlankWindowEnabled(bool value) {
+  HKEY regKey;
+  if (!OpenEarlyBlankWindowRegKey(regKey)) {
+    return;
+  }
+  AutoCloseRegKey closeKey(regKey);
+  DWORD enabled = value;
+  LSTATUS result =
+      ::RegSetValueExW(regKey, L"enabled", 0, REG_DWORD,
+                       reinterpret_cast<PBYTE>(&enabled), sizeof(enabled));
+  if (result != ERROR_SUCCESS) {
+    printf_stderr("Failed persisting enabled to Windows registry\n");
+    return;
+  }
+
+  sEarlyBlankWindowEnabled = true;
+}
+
 }  // namespace mozilla

mozglue/misc/EarlyBlankWindow.h

@@ -17,6 +17,8 @@ MFBT_API HWND ConsumeEarlyBlankWindowHandle();
 MFBT_API void PersistEarlyBlankWindowValues(int screenX, int screenY, int width,
                                             int height,
                                             double cssToDevPixelScaling);
+MFBT_API bool GetEarlyBlankWindowEnabled();
+MFBT_API void SetEarlyBlankWindowEnabled(bool value);
 
 }  // namespace mozilla
 

toolkit/xre/nsAppRunner.cpp

@@ -101,6 +101,7 @@
 #  include <intrin.h>
 #  include <math.h>
 #  include "cairo/cairo-features.h"
+#  include "mozilla/EarlyBlankWindow.h"
 #  include "mozilla/DllPrefetchExperimentRegistryInfo.h"
 #  include "mozilla/WindowsDllBlocklist.h"
 #  include "mozilla/WindowsProcessMitigations.h"
@@ -268,6 +269,13 @@ static const char kPrefSecurityContentSignatureRootHash[] =
     "security.content.signature.root_hash";
 #endif  // defined(MOZ_DEFAULT_BROWSER_AGENT)
 
+#if defined(XP_WIN)
+static const char kPrefThemeId[] = "extensions.activeThemeID";
+static const char kPrefBrowserStartupBlankWindow[] =
+    "browser.startup.blankWindow";
+static const char kPrefPreXulSkeletonUI[] = "browser.startup.preXulSkeletonUI";
+#endif  // defined(XP_WIN)
+
 int gArgc;
 char** gArgv;
 
@@ -1591,6 +1599,33 @@ static void SetupAlteredPrefetchPref() {
                                 PREF_WIN_ALTERED_DLL_PREFETCH);
 }
 
+static void ReflectSkeletonUIPrefToRegistry(const char* aPref, void* aData) {
+  Unused << aPref;
+  Unused << aData;
+
+  bool shouldBeEnabled =
+      Preferences::GetBool(kPrefPreXulSkeletonUI, false) &&
+      Preferences::GetBool(kPrefBrowserStartupBlankWindow, false);
+  if (shouldBeEnabled && Preferences::HasUserValue(kPrefThemeId)) {
+    nsCString themeId;
+    Preferences::GetCString(kPrefThemeId, themeId);
+    shouldBeEnabled = themeId.EqualsLiteral("[email protected]");
+  }
+
+  if (GetEarlyBlankWindowEnabled() != shouldBeEnabled) {
+    SetEarlyBlankWindowEnabled(shouldBeEnabled);
+  }
+}
+
+static void SetupSkeletonUIPrefs() {
+  ReflectSkeletonUIPrefToRegistry(nullptr, nullptr);
+  Preferences::RegisterCallback(&ReflectSkeletonUIPrefToRegistry,
+                                kPrefPreXulSkeletonUI);
+  Preferences::RegisterCallback(&ReflectSkeletonUIPrefToRegistry,
+                                kPrefBrowserStartupBlankWindow);
+  Preferences::RegisterCallback(&ReflectSkeletonUIPrefToRegistry, kPrefThemeId);
+}
+
 #  if defined(MOZ_LAUNCHER_PROCESS)
 
 static void OnLauncherPrefChanged(const char* aPref, void* aData) {
@@ -4625,6 +4660,7 @@ nsresult XREMain::XRE_mainRun() {
     Preferences::RegisterCallbackAndCall(RegisterApplicationRestartChanged,
                                          PREF_WIN_REGISTER_APPLICATION_RESTART);
     SetupAlteredPrefetchPref();
+    SetupSkeletonUIPrefs();
 #  if defined(MOZ_LAUNCHER_PROCESS)
     SetupLauncherProcessPref();
 #  endif  // defined(MOZ_LAUNCHER_PROCESS)