Update from https://crrev.com/316786

cc/layers/video_frame_provider_client_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 CC_LAYERS_VIDEO_FRAME_PROVIDER_CLIENT_IMPL_H_
 #define CC_LAYERS_VIDEO_FRAME_PROVIDER_CLIENT_IMPL_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
 #include "cc/layers/video_frame_provider.h"
 #include "ui/gfx/transform.h"
 
 namespace media { class VideoFrame; }
 
 namespace cc {
 class VideoLayerImpl;
 
 class VideoFrameProviderClientImpl
     : public VideoFrameProvider::Client,
       public base::RefCounted<VideoFrameProviderClientImpl> {
  public:
   static scoped_refptr<VideoFrameProviderClientImpl> Create(
       VideoFrameProvider* provider);
 
   VideoLayerImpl* active_video_layer() { return active_video_layer_; }
-  void set_active_video_layer(VideoLayerImpl* video_layer) {
-    active_video_layer_ = video_layer;
-  }
+  void SetActiveVideoLayer(VideoLayerImpl* video_layer);
 
   void Stop();
-  bool Stopped() const { return !provider_; }
+  bool Stopped();
 
   scoped_refptr<media::VideoFrame> AcquireLockAndCurrentFrame();
   void PutCurrentFrame(const scoped_refptr<media::VideoFrame>& frame);
   void ReleaseLock();
   const gfx::Transform& stream_texture_matrix() const {
     return stream_texture_matrix_;
   }
 
   // VideoFrameProvider::Client implementation. These methods are all callable
   // on any thread.
   void StopUsingProvider() override;
   void DidReceiveFrame() override;
   void DidUpdateMatrix(const float* matrix) override;
 
  private:
   explicit VideoFrameProviderClientImpl(VideoFrameProvider* provider);
   friend class base::RefCounted<VideoFrameProviderClientImpl>;
   ~VideoFrameProviderClientImpl() override;
 
   VideoLayerImpl* active_video_layer_;
 
   // Guards the destruction of provider_ and the frame that it provides
   base::Lock provider_lock_;
   VideoFrameProvider* provider_;
+  base::ThreadChecker thread_checker_;
 
   gfx::Transform stream_texture_matrix_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoFrameProviderClientImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_VIDEO_FRAME_PROVIDER_CLIENT_IMPL_H_