Add a comment for Linux video decode acceleration.

content/renderer/render_view_impl.cc

 // Copyright (c) 2012 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 "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <string>
 #include <vector>
@@ skipping 2357 matching lines @@
     // from the perspective of the audio renderer.
     audio_source_provider = new RenderAudioSourceProvider();
 
     // Add the chrome specific audio renderer, using audio_source_provider
     // as the sink.
     media::AudioRendererImpl* audio_renderer =
         new media::AudioRendererImpl(audio_source_provider);
     collection->AddAudioRenderer(audio_renderer);
   }
 
+  // Accelerated video decode is not enabled by default on Linux.
+  // crbug.com/137247
   bool use_accelerated_video_decode = false;
 #if defined(OS_CHROMEOS)
   use_accelerated_video_decode = true;
 #endif
   use_accelerated_video_decode &= !CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDisableAcceleratedVideoDecode);
   base::WeakPtr<WebGraphicsContext3DCommandBufferImpl> context3d =
       use_accelerated_video_decode ?
       RenderThreadImpl::current()->GetGpuVDAContext3D() :
       base::WeakPtr<WebGraphicsContext3DCommandBufferImpl>();
@@ skipping 3325 matching lines @@
 bool RenderViewImpl::WebWidgetHandlesCompositorScheduling() const {
   return !!RenderThreadImpl::current()->compositor_thread();
 }
 
 void RenderViewImpl::OnJavaBridgeInit() {
   DCHECK(!java_bridge_dispatcher_);
 #if defined(ENABLE_JAVA_BRIDGE)
   java_bridge_dispatcher_ = new JavaBridgeDispatcher(this);
 #endif
 }