Bug 1757031 - Don't restore previous viewport when window size isn't …

…same. r=emilio

Fenix's Picture-In-Picture uses full screen mode. So it isn't same as Firefox
Desktop. When exiting full screen, Fenix's window may not same as before
entering full screen.

When this occurs,

1. When device is portrait orientation, user changes to full screen by content
   script.
2. Fenix enters to full screen then orientation is changed to landscape.
3. User changes that device is changed to landscape by hand.
4. Fenix enters PiP mode. Android (Home screen) change to portrait orientation.
   Then PiP window keeps landscape orientation.
5. When exiting PiP, full screen will be exited.
6. Device is landscape (by Step 3.), so Fenix window is landscape. But Gecko
   restores 1.'s viewport by `nsIDOMWindowUtils.exitFullScreen`. So viewport
   becomes portrait orientation size even if window is landscape orientation.

For PiP mode, although nsIDOMWindowUtils.exitFullScreen is used, it doesn't
consider this situation. So I would like to add non-restore option for it.

Differential Revision: https://phabricator.services.mozilla.com/D143992

dom/base/nsDOMWindowUtils.cpp

@@ -3611,7 +3611,7 @@ nsDOMWindowUtils::HandleFullscreenRequests(bool* aRetVal) {
   return NS_OK;
 }
 
-nsresult nsDOMWindowUtils::ExitFullscreen() {
+nsresult nsDOMWindowUtils::ExitFullscreen(bool aDontRestoreViewSize) {
   PROFILER_MARKER_UNTYPED("Exit fullscreen", DOM);
   nsCOMPtr<Document> doc = GetDocument();
   NS_ENSURE_STATE(doc);
@@ -3627,7 +3627,8 @@ nsresult nsDOMWindowUtils::ExitFullscreen() {
   // set the window dimensions in advance. Since the resize message
   // comes after the fullscreen change call, doing so could avoid an
   // extra resize reflow after this point.
-  PrepareForFullscreenChange(GetDocShell(), oldSize);
+  PrepareForFullscreenChange(GetDocShell(),
+                             aDontRestoreViewSize ? nsSize() : oldSize);
   Document::ExitFullscreenInDocTree(doc);
   return NS_OK;
 }

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -1393,8 +1393,12 @@ interface nsIDOMWindowUtils : nsISupports {
   /**
    * Called when the child frame has fully exit fullscreen, so that the parent
    * process can also fully exit.
+   *
+   * @param aDontResoreViewSize false if content view size is restored by
+   *                            original view size that is on entering full
+   *                            screen.
    */
-  void exitFullscreen();
+  void exitFullscreen([optional] in boolean aDontRestoreViewSize);
 
   /**
    * If sendQueryContentEvent()'s aAdditionalFlags argument is

mobile/android/actors/GeckoViewContentChild.jsm

@@ -23,6 +23,9 @@ const SCREEN_LENGTH_DOCUMENT_HEIGHT = 4;
 const SCROLL_BEHAVIOR_SMOOTH = 0;
 const SCROLL_BEHAVIOR_AUTO = 1;
 
+const SCREEN_ORIENTATION_PORTRAIT = 0;
+const SCREEN_ORIENTATION_LANDSCAPE = 1;
+
 XPCOMUtils.defineLazyModuleGetters(this, {
   E10SUtils: "resource://gre/modules/E10SUtils.jsm",
   PrivacyFilter: "resource://gre/modules/sessionstore/PrivacyFilter.jsm",
@@ -33,6 +36,11 @@ XPCOMUtils.defineLazyModuleGetters(this, {
 var EXPORTED_SYMBOLS = ["GeckoViewContentChild"];
 
 class GeckoViewContentChild extends GeckoViewActorChild {
+  constructor() {
+    super();
+    this.lastOrientation = SCREEN_ORIENTATION_PORTRAIT;
+  }
+
   actorCreated() {
     super.actorCreated();
 
@@ -103,16 +111,32 @@ class GeckoViewContentChild extends GeckoViewActorChild {
     return { history, formdata, scrolldata };
   }
 
+  orientation() {
+    const currentOrientationType = this.contentWindow?.screen.orientation.type;
+    if (!currentOrientationType) {
+      // Unfortunately, we don't know current screen orientation.
+      // Return portrait as default.
+      return SCREEN_ORIENTATION_PORTRAIT;
+    }
+    if (currentOrientationType.startsWith("landscape")) {
+      return SCREEN_ORIENTATION_LANDSCAPE;
+    }
+    return SCREEN_ORIENTATION_PORTRAIT;
+  }
+
   receiveMessage(message) {
     const { name } = message;
     debug`receiveMessage: ${name}`;
 
     switch (name) {
       case "GeckoView:DOMFullscreenEntered":
+        this.lastOrientation = this.orientation();
         this.contentWindow?.windowUtils.handleFullscreenRequests();
         break;
       case "GeckoView:DOMFullscreenExited":
-        this.contentWindow?.windowUtils.exitFullscreen();
+        // During fullscreen, window size is changed. So don't restore viewport size.
+        const restoreViewSize = this.orientation() == this.lastOrientation;
+        this.contentWindow?.windowUtils.exitFullscreen(!restoreViewSize);
         break;
       case "GeckoView:ZoomToInput": {
         const { contentWindow } = this;