Do not use overlays when VR shell is enabled.

media/blink/webmediaplayer_impl.h

Index: media/blink/webmediaplayer_impl.h
diff --git a/media/blink/webmediaplayer_impl.h b/media/blink/webmediaplayer_impl.h
index 020adcea097348c4a25ddcf5e7fe15aac47540d1..e25fde009f94d17a24ad896a3fc0ecb3a0a3f209 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -178,6 +178,7 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
       blink::WebContentDecryptionModule* cdm,
       blink::WebContentDecryptionModuleResult result) override;
 
+  void SetEnableFullscreenOverlays(bool enable_overlays);
   bool supportsOverlayFullscreenVideo() override;
   void enteredFullscreen() override;
   void exitedFullscreen() override;
@@ -532,12 +533,15 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   // cleared by the decoder.
   SurfaceCreatedCB set_surface_cb_;
 
-  // Force to use SurfaceView instead of SurfaceTexture on Android.
+  // On Android an overlay surface means using
+  // SurfaceView instead of SurfaceTexture.
+
+  // Force using video overlays for all uses of WMPI.

[ddorwin, 2016/12/16 19:15:18]

nit: WMPI is the class, so "this class" might be better.

However, "all uses" may not be correct. It's not correct for audio-only and
maybe not even all video (e.g., off screen).

Maybe "Use overlays for all video."

[amp, 2016/12/16 19:25:03]

Done.

   bool force_video_overlays_;
 
-  // Prevent use of SurfaceView on Android. (Ignored when
-  // |force_video_overlays_| is true.)
-  bool disable_fullscreen_video_overlays_;
+  // Use overlays for fullscreen video.
+  // (Implied if |force_video_overlays_| is true.)
+  bool enable_fullscreen_video_overlays_;
 
   // Suppresses calls to OnPipelineError() after destruction / shutdown has been
   // started; prevents us from spuriously logging errors that are transient or