Fix Media.Video.KeyFrameDistance metric calculation

media/filters/decoder_stream_traits.cc

 // Copyright 2014 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.
 
 #include "media/filters/decoder_stream_traits.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "media/base/audio_buffer.h"
 #include "media/base/audio_decoder.h"
@@ skipping 119 matching lines @@
   if (buffer->end_of_stream()) {
     last_keyframe_timestamp_ = base::TimeDelta();
     return;
   }
 
   if (!buffer->is_key_frame())
     return;
 
   base::TimeDelta current_frame_timestamp = buffer->timestamp();
   if (last_keyframe_timestamp_.is_zero()) {
     last_keyframe_timestamp_ = current_frame_timestamp;

[sandersd (OOO until July 31), 2017/01/03 23:41:41]

Looks like this should just not be conditional here, rather than duplicating the
code.

[whywhat, 2017/01/04 01:00:14]

You mean something like:

if (!last_kf_ts_.is_zero()) {
  UMA_HISTOGRAM_MEDIUM_TIMES(...);
}

last_kf_ts_ = cur_f_ts;

     return;
   }
 
   UMA_HISTOGRAM_MEDIUM_TIMES(
       "Media.Video.KeyFrameDistance",
       current_frame_timestamp - last_keyframe_timestamp_);
+  last_keyframe_timestamp_ = current_frame_timestamp;
 }
 
 }  // namespace media