services/ui: Detect when a video is playing

cc/layers/video_layer.cc

 // Copyright 2010 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.
 
 #include "cc/layers/video_layer.h"
 
 #include "cc/layers/video_layer_impl.h"
 
 namespace cc {
 
 scoped_refptr<VideoLayer> VideoLayer::Create(
     VideoFrameProvider* provider,
     media::VideoRotation video_rotation) {
   return make_scoped_refptr(new VideoLayer(provider, video_rotation));
 }
 
 VideoLayer::VideoLayer(VideoFrameProvider* provider,
                        media::VideoRotation video_rotation)
     : provider_(provider), video_rotation_(video_rotation) {
+  SetMayContainVideo(true);
   DCHECK(provider_);
 }
 
 VideoLayer::~VideoLayer() {}
 
 std::unique_ptr<LayerImpl> VideoLayer::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return VideoLayerImpl::Create(tree_impl, id(), provider_, video_rotation_);
 }
 
 bool VideoLayer::Update() {
   bool updated = Layer::Update();
 
   // Video layer doesn't update any resources from the main thread side,
   // but repaint rects need to be sent to the VideoLayerImpl via commit.
   //
   // This is the inefficient legacy redraw path for videos.  It's better to
   // communicate this directly to the VideoLayerImpl.
   updated |= !update_rect().IsEmpty();
 
   return updated;
 }
 
 void VideoLayer::StopUsingProvider() {
   provider_ = nullptr;
 }
 
 }  // namespace cc