Add Media.AudioRendererEvents histogram to measure how often OnRenderError() is called.

tools/metrics/histograms/histograms.xml

 <!--
 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.
 -->
 
 <!--
 This file is used to generate a comprehensive list of Chrome histograms along
 with a detailed description for each histogram.
 
@@ skipping 496 matching lines @@
   <summary>
     Time Non-IDB LevelDBEnv slept before successfully completing this operation.
     0 means success on the first try.
   </summary>
 </histogram>
 
 <histogram name="Linux.GlibcVersion" enum="LinuxGlibcVersion">
   <summary>The version of glibc used. (Linux only)</summary>
 </histogram>
 
+<histogram name="Media.AudioRendererSinkErrors">
+  <summary>
+    False is recorded whenever AudioRendererImpl successfully initializes an

[jar (doing other things), 2013/04/24 21:51:07]

You should add an enum to make this more readable:

0   Initialized
1   Terminated with Error

[scherkus (not reviewing), 2013/04/25 00:04:46]

Done.

+    AudioRendererSink. True is recorded whenever a successful initialization
+    follows with the sink reporting OnRenderError().

[jar (doing other things), 2013/04/24 21:51:07]

nit: "follows with" --> "is followed by the"

[scherkus (not reviewing), 2013/04/25 00:04:46]

Reworded a bit. Mind taking another scan?

+  </summary>
+</histogram>
+
 <histogram name="Media.DetectedAudioCodec" enum="FFmpegCodecs">
   <summary>Audio codec used in HTML5 media.</summary>
 </histogram>
 
 <histogram name="Media.DetectedVideoCodec" enum="FFmpegCodecs">
   <summary>Video codec used in HTML5 media.</summary>
 </histogram>
 
 <histogram name="Media.VAVDAH264.DecoderFailure" enum="VAVDAH264DecoderFailure">
   <summary>
@@ skipping 6883 matching lines @@
 <fieldtrial name="SSLResumption">
   <group name="Resume_Handshake" label="Session Resumption"/>
   <group name="Full_Handshake" label="Full"/>
   <affected-histogram name="Net.SSL_Connection_Latency"/>
   <affected-histogram name="Net.SSL_Connection_Latency_Google"/>
 </fieldtrial>
 
 </fieldtrials>
 
 </histogram-configuration>