RtcVideo{Encoder,Decoder}{Factory,} minor cleanup: consts, range based loops, comments.

content/renderer/media/rtc_video_decoder_factory.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 CONTENT_RENDERER_MEDIA_RTC_VIDEO_DECODER_FACTORY_H_
 #define CONTENT_RENDERER_MEDIA_RTC_VIDEO_DECODER_FACTORY_H_
 
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/threading/thread.h"
 #include "content/common/content_export.h"
@@ skipping 21 matching lines @@
   // Runs on Chrome_libJingle_WorkerThread. The child thread is blocked while
   // this runs.
   webrtc::VideoDecoder* CreateVideoDecoder(
       webrtc::VideoCodecType type) override;
 
   // Runs on Chrome_libJingle_WorkerThread. The child thread is blocked while
   // this runs.
   void DestroyVideoDecoder(webrtc::VideoDecoder* decoder) override;
 
  private:
-  scoped_refptr<media::GpuVideoAcceleratorFactories> gpu_factories_;
+  const scoped_refptr<media::GpuVideoAcceleratorFactories> gpu_factories_;
 
   DISALLOW_COPY_AND_ASSIGN(RTCVideoDecoderFactory);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_RTC_VIDEO_DECODER_FACTORY_H_