Associate "score" attribute with SSIM so that future perf graphs know that an increase in SSIM shou…

webrtc/video/video_quality_test.cc

 /*
  *  Copyright (c) 2015 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.
  */
 #include <stdio.h>
@@ skipping 456 matching lines @@
   bool FrameProcessed() {
     rtc::CritScope crit(&comparison_lock_);
     ++frames_processed_;
     assert(frames_processed_ <= frames_to_process_);
     return frames_processed_ == frames_to_process_;
   }
 
   void PrintResults() {
     rtc::CritScope crit(&comparison_lock_);
     PrintResult("psnr", psnr_, " dB");
-    PrintResult("ssim", ssim_, "");
+    PrintResult("ssim", ssim_, " score");
     PrintResult("sender_time", sender_time_, " ms");
     printf("RESULT dropped_frames: %s = %d frames\n", test_label_.c_str(),
            dropped_frames_);
     PrintResult("receiver_time", receiver_time_, " ms");
     PrintResult("total_delay_incl_network", end_to_end_, " ms");
     PrintResult("time_between_rendered_frames", rendered_delta_, " ms");
     PrintResult("encoded_frame_size", encoded_frame_size_, " bytes");
     PrintResult("encode_frame_rate", encode_frame_rate_, " fps");
     PrintResult("encode_time", encode_time_ms, " ms");
     PrintResult("encode_usage_percent", encode_usage_percent, " percent");
@@ skipping 599 matching lines @@
   video_send_stream_->Stop();
   receive_stream->Stop();
 
   call->DestroyVideoReceiveStream(receive_stream);
   call->DestroyVideoSendStream(video_send_stream_);
 
   transport.StopSending();
 }
 
 }  // namespace webrtc