Explicitly represent "no surface ID yet" in WMPI.

media/blink/webmediaplayer_impl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 #define MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 608 matching lines @@
 
   std::unique_ptr<RendererFactory> renderer_factory_;
 
   // For requesting surfaces on behalf of the Android H/W decoder in fullscreen.
   // This will be null everywhere but Android.
   SurfaceManager* surface_manager_;
 
   // For canceling ongoing surface creation requests when exiting fullscreen.
   base::CancelableCallback<void(int)> surface_created_cb_;
 
-  // The current overlay surface id. Populated while in fullscreen once the
-  // surface is created.
-  int overlay_surface_id_;
+  // The current overlay surface id. Populated, possibly with kNoSurfaceID if
+  // we're not supposed to use an overlay, unless we have an outstanding surface
+  // request to the SurfaceManager.
+  base::Optional<int> overlay_surface_id_;
 
   // If a surface is requested before it's finished being created, the request
   // is saved and satisfied once the surface is available. If the decoder does
   // not require restart to change surfaces, this is callback is kept until
   // cleared by the decoder.
   SurfaceCreatedCB set_surface_cb_;
 
   // On Android an overlay surface means using
   // SurfaceView instead of SurfaceTexture.
 
@@ skipping 82 matching lines @@
   base::CancelableCallback<void(base::TimeTicks)> frame_time_report_cb_;
 
   bool initial_video_height_recorded_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_