[Picture in Picture] Check DisplayType when exiting Picture-in-Picture.

Change-Id: I01418997ece8abc89d5556df7c2439972ad8e348
Reviewed-on: https://chromium-review.googlesource.com/1108567
Commit-Queue: apacible <apacible@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569559}

media/blink/webmediaplayer_impl.cc

@@ -2126,8 +2126,12 @@ void WebMediaPlayerImpl::OnPictureInPictureModeEnded() {
   // for validity.
   DCHECK(pip_surface_id_.is_valid());
 
-  if (client_)
+  // It is possible for |pip_surface_id_| to be valid when |client_| is not in
+  // Picture-in-Picture mode. In this case, do nothing.
+  if (client_ && client_->DisplayType() ==
+                     WebMediaPlayer::DisplayType::kPictureInPicture) {
     client_->PictureInPictureStopped();
+  }
 }
 
 void WebMediaPlayerImpl::ScheduleRestart() {