Add UMA histograms for WebAudio

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 58c7654fd9861cf3f0fb2a1a54e8451fdbe6d0d9..dbd7b8621540d1e26f35a787be43a213883963cd 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -59173,6 +59173,61 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="WebAudio.AudioBuffer.Length">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The length (in frames) requested by createBuffer(). Recorded for every call
+    to createBuffer().
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.AudioBuffer.NumberOfChannels">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The number of channels requested by createBuffer(). Recorded for every call
+    to createBuffer().
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.AudioBuffer.SampleRate">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The sample rate (in Hz) requested by createBuffer(). Recorded for every call
+    to createBuffer().
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.AudioBuffer.SampleRateRatio">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The ratio of the buffer sample rate from createBuffer() to the context
+    sample rate multiplied by 100. This indicates if the buffer needs to be
+    resampled. Recorded for every call to createBuffer().
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.AudioContext.MaxChannelCount">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The maximum number of (hardware) channels available in an AudioContext.
+    Recorded for every WebAudio AudioContext that is created.
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.AudioContext.SampleRate">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The hardware sample rate (in Hz) used by an AudioContext. Recorded for every
+    WebAudio AudioContext that is created.
+  </summary>
+</histogram>
+
 <histogram name="WebAudio.AudioDestination.CallbackBufferSize">
   <owner>rtoy@chromium.org</owner>
   <owner>hongchan@chromium.org</owner>
@@ -59215,6 +59270,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="WebAudio.BiquadFilter.Type">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The type of the BiquadFilterNode. (0=Lowpass, 1=Highpass, 2=Bandpass,
+    3=Lowshelf, 4=Highshelf, 5=Peaking, 6=Notch, 7=Allpass).  Recorded each time
+    the type is set.
+  </summary>
+</histogram>
+
 <histogram name="WebAudio.IIRFilterNode.Order">
   <owner>rtoy@chromium.org</owner>
   <owner>hongchan@chromium.org</owner>
@@ -59225,6 +59290,42 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="WebAudio.OfflineAudioContext.ChannelCount">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The number of channels specified for the offline audio context. Recorded for
+    every offline context created.
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.OfflineAudioContext.Length">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The length (in frames) specified for the offline audio context. Recorded for
+    every offline context created.
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.OfflineAudioContext.SampleRate">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The sample rate (in Hz) specified for the offline audio context. Recorded
+    for every offline context created.
+  </summary>
+</histogram>
+
+<histogram name="WebAudio.PannerNode.PanningModel">
+  <owner>rtoy@chromium.org</owner>
+  <owner>hongchan@chromium.org</owner>
+  <summary>
+    The panning model (&quot;equalpower&quot; = 0, &quot;HRTF&quot; = 1) for the
+    PannerNode. Recorded every time the panning model is changed.
+  </summary>
+</histogram>
+
 <histogram name="WebController.CertVerificationErrorsCacheHit"
     enum="BooleanCacheHit">
   <owner>eugenebut@chromium.org</owner>