Adding more detailed UMA histogram for detection of output audio glitches

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index bff5da0e325dbb4ac324563d48c8ad4799740da1..db91a3c5a67b7fd223be3e9c9da38415827c07cf 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -11056,6 +11056,14 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Media.AudioRendererAudioGlitches" enum="AudioGlitchResult">
+  <owner>henrika@chromium.org</owner>
+  <summary>
+    Captures if render-side audio glitches are detected or not. Sampled once
+    when a low-latency output audio stream is destructed.

[Alexei Svitkine (slow), 2014/09/02 15:20:10]

Nit: I'd reword this to be a little bit more clear -> "Sampled when a
low-latency output audio stream is destructed." (Since "once" can be confusing.)

+  </summary>
+</histogram>
+
 <histogram name="Media.AudioRendererEvents" enum="AudioRendererEvents">
   <owner>scherkus@chromium.org</owner>
   <summary>Captures statistics for various AudioRendererImpl events.</summary>
@@ -37672,6 +37680,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="8" label="k1920"/>
 </enum>
 
+<enum name="AudioGlitchResult" type="int">
+  <int value="0" label="No audio glitches"/>
+  <int value="1" label="Audio glitches"/>
+</enum>
+
 <enum name="AudioInputSilenceReport" type="int">
   <int value="0" label="No measurement"/>
   <int value="1" label="Only audio"/>