Changeset 280358 in webkit

Timestamp:

Jul 27, 2021 4:19:32 PM (12 months ago)

Author:

Peng Liu

Message:

Safari hangs when entering PiP from (element) fullscreen
​https://bugs.webkit.org/show_bug.cgi?id=228332

Reviewed by Eric Carlson.

When a video element's ancestor element is in fullscreen and the video element
is entering picture-in-picture, WKFullScreenWindowController in the UI process
will notify the WebContent process that the ancestor element needs to exit fullscreen.
However, some sites call document.webkitExitFullscreen() to request the ancestor
element to exit fullscreen proactively. Both WebContent process and UI process will
try to do the same thing and may lead to a race condition.

That was not an issue before r274460 because WebFullScreenManager::requestExitFullScreen()
will ignore the request from the UI process if the WebContent process has already
started the steps to exit fullscreen.

This patch stops the UI process sending the exit fullscreen request if a WebContent
process has started the steps to exit fullscreen.

Manually tested.

• UIProcess/mac/WKFullScreenWindowController.mm:

(-[WKFullScreenWindowController didEnterPictureInPicture]):

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• UIProcess/mac/WKFullScreenWindowController.mm (modified) (1 diff)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2021-07-27  Peng Liu  <peng.liu6@apple.com>
+
+        Safari hangs when entering PiP from (element) fullscreen
+        https://bugs.webkit.org/show_bug.cgi?id=228332
+
+        Reviewed by Eric Carlson.
+
+        When a video element's ancestor element is in fullscreen and the video element
+        is entering picture-in-picture, `WKFullScreenWindowController` in the UI process
+        will notify the WebContent process that the ancestor element needs to exit fullscreen.
+        However, some sites call `document.webkitExitFullscreen()` to request the ancestor
+        element to exit fullscreen proactively. Both WebContent process and UI process will
+        try to do the same thing and may lead to a race condition.
+
+        That was not an issue before r274460 because `WebFullScreenManager::requestExitFullScreen()`
+        will ignore the request from the UI process if the WebContent process has already
+        started the steps to exit fullscreen.
+
+        This patch stops the UI process sending the exit fullscreen request if a WebContent
+        process has started the steps to exit fullscreen.
+
+        Manually tested.
+
+        * UIProcess/mac/WKFullScreenWindowController.mm:
+        (-[WKFullScreenWindowController didEnterPictureInPicture]):
+
 2021-07-27  Myles C. Maxfield  <mmaxfield@apple.com>
 

trunk/Source/WebKit/UIProcess/mac/WKFullScreenWindowController.mm

@@ -642 +642 @@
 - (void)didEnterPictureInPicture
 {
-    [self requestExitFullScreen];
+    if ([self isFullScreen])
+        [self requestExitFullScreen];
 }