WeakPtrFactory

. (cla: yes)

20905 Fix race condition in OnPlatformViewDestroyDisablesThreadMerger (cla: yes)

20910 Wait for first frame before checking layer tree (cla: yes)

20912 Pass text input key events to the EventResponder if they do not yield characters (cla: yes, platform-android)

20914 [web] migrate from e2e to integration_test (cla: yes)

20915 improve sensitivity of BackdropFilter web tests (cla: yes)

20916 Ensure the destructor is called since it destroys the EGLSurface before creating a new onscreen surface. (cla: yes, platform-android)

20921 [Android R] Integrate DisplayCutouts into viewportMetrics (cla: yes, platform-android, waiting for tree to go green)