[iOS WK2] CADisplayLink in the web process is used unintentionally

smfr · smfr · commit 2e989dc445d7 · 2021-04-10T04:09:04.000Z
https://bugs.webkit.org/show_bug.cgi?id=224395 Reviewed by Tim Horton. When RemoteLayerTreeDrawingArea called windowScreenDidChange() from its constructor, m_page.drawingArea() was null which resulted in DisplayRefreshMonitor::create() receiving a null DisplayRefreshMonitorFactory*, so it fell back to the legacy DisplayRefreshMonitorIOS, instead of using RemoteLayerTreeDisplayRefreshMonitor. Fix by sending windowScreenDidChange() from the UI process, with the synthetic DisplayID generated from the webPageID(). This has the advantage that WebPageProxy will also store the correct DisplayID, and is more similar to macOS. * UIProcess/ios/WKContentView.mm: (-[WKContentView _commonInitializationWithProcessPool:configuration:]): * WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm: (WebKit::RemoteLayerTreeDrawingArea::RemoteLayerTreeDrawingArea): Canonical link: https://commits.webkit.org/236363@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@275792 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
@@ -1,3 +1,24 @@
+2021-04-09  Simon Fraser  <simon.fraser@apple.com>
+
+        [iOS WK2] CADisplayLink in the web process is used unintentionally
+        https://bugs.webkit.org/show_bug.cgi?id=224395
+
+        Reviewed by Tim Horton.
+
+        When RemoteLayerTreeDrawingArea called windowScreenDidChange() from its constructor,
+        m_page.drawingArea() was null which resulted in DisplayRefreshMonitor::create()
+        receiving a null DisplayRefreshMonitorFactory*, so it fell back to the legacy
+        DisplayRefreshMonitorIOS, instead of using RemoteLayerTreeDisplayRefreshMonitor.
+
+        Fix by sending windowScreenDidChange() from the UI process, with the synthetic
+        DisplayID generated from the webPageID(). This has the advantage that
+        WebPageProxy will also store the correct DisplayID, and is more similar to macOS.
+
+        * UIProcess/ios/WKContentView.mm:
+        (-[WKContentView _commonInitializationWithProcessPool:configuration:]):
+        * WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm:
+        (WebKit::RemoteLayerTreeDrawingArea::RemoteLayerTreeDrawingArea):
+
 2021-04-09  Wenson Hsieh  <wenson_hsieh@apple.com>
 
         REGRESSION (r271660): Tap highlight no longer shows when tapping clickable elements without touch event listeners
diff --git a/Source/WebKit/UIProcess/ios/WKContentView.mm b/Source/WebKit/UIProcess/ios/WKContentView.mm
@@ -174,6 +174,13 @@ - (instancetype)_commonInitializationWithProcessPool:(WebKit::WebProcessPool&)pr
     _page->setDelegatesScrolling(true);
     _page->setScreenIsBeingCaptured([[[self window] screen] isCaptured]);
 
+    // In order to ensure that we get a unique DisplayRefreshMonitor per-DrawingArea (necessary because DisplayRefreshMonitor
+    // is driven by this class), give each page a unique DisplayID derived from WebPage's unique ID.
+    // FIXME: While using the high end of the range of DisplayIDs makes a collision with real, non-RemoteLayerTreeDrawingArea
+    // DisplayIDs less likely, it is not entirely safe to have a RemoteLayerTreeDrawingArea and TiledCoreAnimationDrawingArea
+    // coeexist in the same process.
+    _page->windowScreenDidChange(std::numeric_limits<uint32_t>::max() - _page->webPageID().toUInt64(), WTF::nullopt);
+
 #if ENABLE(FULLSCREEN_API)
     _page->setFullscreenClient(makeUnique<WebKit::FullscreenClient>(self.webView));
 #endif
diff --git a/Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm b/Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm
@@ -67,13 +67,6 @@
 
     m_commitQueue = adoptOSObject(dispatch_queue_create("com.apple.WebKit.WebContent.RemoteLayerTreeDrawingArea.CommitQueue", nullptr));
 
-    // In order to ensure that we get a unique DisplayRefreshMonitor per-DrawingArea (necessary because DisplayRefreshMonitor
-    // is driven by this class), give each page a unique DisplayID derived from WebPage's unique ID.
-    // FIXME: While using the high end of the range of DisplayIDs makes a collision with real, non-RemoteLayerTreeDrawingArea
-    // DisplayIDs less likely, it is not entirely safe to have a RemoteLayerTreeDrawingArea and TiledCoreAnimationDrawingArea
-    // coeexist in the same process.
-    webPage.windowScreenDidChange(std::numeric_limits<uint32_t>::max() - webPage.identifier().toUInt64(), WTF::nullopt);
-
     if (auto viewExposedRect = parameters.viewExposedRect)
         setViewExposedRect(viewExposedRect);
 }
