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

content/renderer/media/rtc_video_encoder.h

Index: content/renderer/media/rtc_video_encoder.h
diff --git a/content/renderer/media/rtc_video_encoder.h b/content/renderer/media/rtc_video_encoder.h
index 917e4b4e5696b27d6519f76dbc542711ae434f41..e979ac88e61917e6072aa234caedaf2d7d34e6ea 100644
--- a/content/renderer/media/rtc_video_encoder.h
+++ b/content/renderer/media/rtc_video_encoder.h
@@ -18,15 +18,11 @@
 #include "ui/gfx/geometry/size.h"
 
 namespace base {
-
 class MessageLoopProxy;
-
 }  // namespace base
 
 namespace media {
-
 class GpuVideoAcceleratorFactories;
-
 }  // namespace media
 
 namespace content {
@@ -85,7 +81,7 @@ class CONTENT_EXPORT RTCVideoEncoder
   const webrtc::VideoCodecType video_codec_type_;
 
   // Factory for creating VEAs, shared memory buffers, etc.
-  scoped_refptr<media::GpuVideoAcceleratorFactories> gpu_factories_;
+  const scoped_refptr<media::GpuVideoAcceleratorFactories> gpu_factories_;
 
   // webrtc::VideoEncoder encode complete callback.
   webrtc::EncodedImageCallback* encoded_image_callback_;