Fix overreporting of '0' stats in the Mac audio rendering code.

media/audio/mac/audio_auhal_mac.cc

 // Copyright 2013 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/audio/mac/audio_auhal_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 131 matching lines @@
     // Use a cancellable closure so that if Stop() is called before Start()
     // actually runs, we can cancel the pending start.
     deferred_start_cb_.Reset(
         base::Bind(&AUHALStream::Start, base::Unretained(this), callback));
     manager_->GetTaskRunner()->PostDelayedTask(
         FROM_HERE, deferred_start_cb_.callback(), base::TimeDelta::FromSeconds(
             AudioManagerMac::kStartDelayInSecsForPowerEvents));
     return;
   }
 
-  ReportAndResetStats();
-
   stopped_ = false;
   audio_fifo_.reset();
   {
     base::AutoLock auto_lock(source_lock_);
     source_ = callback;
   }
 
   OSStatus result = AudioOutputUnitStart(audio_unit_);
   if (result == noErr)
     return;
 
   Stop();
   OSSTATUS_DLOG(ERROR, result) << "AudioOutputUnitStart() failed.";
   callback->OnError(this);
 }
 
 void AUHALStream::Stop() {
   DCHECK(thread_checker_.CalledOnValidThread());
   deferred_start_cb_.Cancel();
   if (stopped_)
     return;
 
   OSStatus result = AudioOutputUnitStop(audio_unit_);
   OSSTATUS_DLOG_IF(ERROR, result != noErr, result)
       << "AudioOutputUnitStop() failed.";
   if (result != noErr)
     source_->OnError(this);
 
+  ReportAndResetStats();
+
   base::AutoLock auto_lock(source_lock_);
   source_ = NULL;
   stopped_ = true;
 }
 
 void AUHALStream::SetVolume(double volume) {
   volume_ = static_cast<float>(volume);
 }
 
 void AUHALStream::GetVolume(double* volume) {
@@ skipping 172 matching lines @@
         largest_glitch_frames_ = lost_frames;
       ++glitches_detected_;
     }
   }
 
   // Store the last sample time for use next time we get called back.
   last_sample_time_ = timestamp->mSampleTime;
 }
 
 void AUHALStream::ReportAndResetStats() {
+  if (!last_sample_time_)
+    return;  // No stats gathered to report.
+
   // A value of 0 indicates that we got the buffer size we asked for.
   UMA_HISTOGRAM_COUNTS("Media.Audio.Render.FramesRequested",
                        number_of_frames_requested_);
   // Even if there aren't any glitches, we want to record it to get a feel for
   // how often we get no glitches vs the alternative.
-  UMA_HISTOGRAM_COUNTS("Media.Audio.Render.Glitches", glitches_detected_);
+  UMA_HISTOGRAM_CUSTOM_COUNTS("Media.Audio.Render.Glitches", glitches_detected_,
+                              0, 999999, 100);
 
   if (glitches_detected_ != 0) {
     auto lost_frames_ms = (total_lost_frames_ * 1000) / params_.sample_rate();
     UMA_HISTOGRAM_COUNTS("Media.Audio.Render.LostFramesInMs", lost_frames_ms);
     auto largest_glitch_ms =
         (largest_glitch_frames_ * 1000) / params_.sample_rate();
     UMA_HISTOGRAM_COUNTS("Media.Audio.Render.LargestGlitchMs",
                          largest_glitch_ms);
     DLOG(WARNING) << "Total glitches=" << glitches_detected_
                   << ". Total frames lost=" << total_lost_frames_ << " ("
@@ skipping 143 matching lines @@
   OSStatus result = AudioUnitUninitialize(audio_unit_);
   OSSTATUS_DLOG_IF(ERROR, result != noErr, result)
       << "AudioUnitUninitialize() failed.";
   result = AudioComponentInstanceDispose(audio_unit_);
   OSSTATUS_DLOG_IF(ERROR, result != noErr, result)
       << "AudioComponentInstanceDispose() failed.";
   audio_unit_ = 0;
 }
 
 }  // namespace media