Add field trial for balanced degradation preference.

webrtc/video_send_stream.h

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 206 matching lines @@
 
   // Based on the spec in
   // https://w3c.github.io/webrtc-pc/#idl-def-rtcdegradationpreference.
   // These options are enforced on a best-effort basis. For instance, all of
   // these options may suffer some frame drops in order to avoid queuing.
   // TODO(sprang): Look into possibility of more strictly enforcing the
   // maintain-framerate option.
   enum class DegradationPreference {
     // Don't take any actions based on over-utilization signals.
     kDegradationDisabled,
-    // On over-use, request lost resolution, possibly causing down-scaling.
+    // On over-use, request lower frame rate, possibly causing frame drops.
     kMaintainResolution,
-    // On over-use, request lower frame rate, possible causing frame drops.
+    // On over-use, request lower resolution, possibly causing down-scaling.
     kMaintainFramerate,
     // Try to strike a "pleasing" balance between frame rate or resolution.
     kBalanced,
   };
 
   virtual void SetSource(
       rtc::VideoSourceInterface<webrtc::VideoFrame>* source,
       const DegradationPreference& degradation_preference) = 0;
 
   // Set which streams to send. Must have at least as many SSRCs as configured
@@ skipping 19 matching lines @@
     EnableEncodedFrameRecording(std::vector<rtc::PlatformFile>(), 0);
   }
 
  protected:
   virtual ~VideoSendStream() {}
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_SEND_STREAM_H_