Add initial bitrate and frame resolution parameters to quality scaler.

webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc

 /*
  *  Copyright (c) 2012 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 583 matching lines @@
           stream_bitrates[stream_idx], inst->maxBitrate, inst->maxFramerate,
           &configurations_[i]);
     }
   }
 
   rps_.Init();
   // Disable both high-QP limits and framedropping. Both are handled by libvpx
   // internally.
   const int kDisabledBadQpThreshold = 64;
   quality_scaler_.Init(codec_.qpMax / QualityScaler::kDefaultLowQpDenominator,
-                       kDisabledBadQpThreshold, false);
+                       kDisabledBadQpThreshold, false, 0, 0, 0);

[pbos-webrtc, 2016/02/10 13:43:21]

I'd like to have this here as well, as I think the issue impacts all platforms.

[AlexG, 2016/02/10 19:07:16]

I think it is too early to enable this on all platforms - I guess BWE estimation
will converge pretty fast in typical use cases resulting in unnecessary 5
seconds delay when switching to HD.
I think to postpone this change in either follow up CL or until we can get
configurable windows.

[pbos-webrtc, 2016/02/10 19:12:27]

Initial bitrates, including keyframes, look bad at the initial 300k but VGA at
HD bitrate looks really good. The only thing I'm a bit curious of is if the good
QP thresholds always allow us to go back up.

I think you might postpone it but please put a TODO here. sprang@: Consider
checking this out. :)

   quality_scaler_.ReportFramerate(codec_.maxFramerate);
 
   // Only apply scaling to improve for single-layer streams. The scaling metrics
   // use frame drops as a signal and is only applicable when we drop frames.
   quality_scaler_enabled_ = encoders_.size() == 1 &&
                             configurations_[0].rc_dropframe_thresh > 0 &&
                             codec_.codecSpecific.VP8.automaticResizeOn;
 
   return InitAndSetControlSettings();
 }
@@ skipping 785 matching lines @@
     return -1;
   }
   if (vpx_codec_control(copy->decoder_, VP8_SET_REFERENCE, ref_frame_) !=
       VPX_CODEC_OK) {
     return -1;
   }
   return 0;
 }
 
 }  // namespace webrtc