Protect WMPI::ActivateSurfaceLayerForVideo From Multiple Invocations

If ActivateSurfaceLayerForVideo is invoked more than once it will cause
a breakpoint crash when it attempts to run the OnceCallback
`create_bridge_callback_` a second time.

This change helps protect against this by moving the onus for checking
whether `surface_layer_for_video_enabled_` is set from the callers
of ActivateSurfaceLayerForVideo and instead adds a check directly in
ActivateSurfaceLayerForVideo.

Bug: 1502638
Change-Id: I49933b0b5b3d0f7ed0bb969e48eb4939187b8c2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5035701
Reviewed-by: Frank Liberato <liberato@chromium.org>
Reviewed-by: Frank Li <frankli@microsoft.com>
Commit-Queue: William Carr <wicarr@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1225689}

third_party/blink/renderer/platform/media/web_media_player_impl.cc

@@ -1132,8 +1132,7 @@ void WebMediaPlayerImpl::SetWasPlayedWithUserActivation(
 }
 
 void WebMediaPlayerImpl::OnRequestPictureInPicture() {
-  if (!surface_layer_for_video_enabled_)
-    ActivateSurfaceLayerForVideo();
+  ActivateSurfaceLayerForVideo();
 
   DCHECK(bridge_);
   DCHECK(bridge_->GetSurfaceId().is_valid());
@@ -2008,7 +2007,10 @@ void WebMediaPlayerImpl::OnMetadata(const media::PipelineMetadata& metadata) {
 
 void WebMediaPlayerImpl::ActivateSurfaceLayerForVideo() {
   // Note that we might or might not already be in VideoLayer mode.
-  DCHECK(!bridge_);
+  if (surface_layer_for_video_enabled_) {
+    // Surface layer has already been activated.
+    return;
+  }
 
   surface_layer_for_video_enabled_ = true;