Mixing audio with different latency requirements

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 68928e41b0bd17fea6c4f6287762d8517ac359c0..3427456fa540a98358444b246fcfdb241ec7074b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -20917,6 +20917,64 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Media.Audio.Render.AudioInputsPerMixer.LatencyExact"
+    units="inputs">
+  <owner>olka@chromium.org</owner>
+  <summary>
+    Number of simultaneous inputs coming to the AudioRendererMixer rendering

[tommi (sloooow) - chröme, 2016/06/28 14:14:54]

I'm having some problems parsing the description.  Let me see if my
understanding is correct:

Number of simultaneous inputs with user specified latency, mixed by an
AudioRendererMixer.
The captured value will be the highest number of inputs at any point throughout
the lifetime of the mixer instance.
It is useful for ...

is that correct? (I'm not sure I got the part about latency right)

+    audio with the latency of the exact value specified by the user. The value
+    is lifetime maximum logged on the mixer destruction. It is useful for
+    evaluating how mixing audio in renderer reduces the number of output audio
+    streams going from the renderer to the browser.
+  </summary>
+</histogram>
+
+<histogram name="Media.Audio.Render.AudioInputsPerMixer.LatencyInteractive"
+    units="inputs">
+  <owner>olka@chromium.org</owner>
+  <summary>
+    Number of simultaneous inputs coming to the AudioRendererMixer rendering
+    audio with interactive latency. The value is lifetime maximum logged on the
+    mixer destruction. It is useful for evaluating how mixing audio in renderer
+    reduces the number of output audio streams going from the renderer to the
+    browser.
+  </summary>
+</histogram>
+
+<histogram name="Media.Audio.Render.AudioInputsPerMixer.LatencyPlayback"
+    units="inputs">
+  <owner>olka@chromium.org</owner>
+  <summary>
+    Number of simultaneous inputs coming to the AudioRendererMixer rendering
+    audio with playback latency. The value is lifetime maximum logged on the
+    mixer destruction. It is useful for evaluating how mixing audio in renderer
+    reduces the number of output audio streams going from the renderer to the
+    browser.
+  </summary>
+</histogram>
+
+<histogram name="Media.Audio.Render.AudioInputsPerMixer.LatencyRtc"
+    units="inputs">
+  <owner>olka@chromium.org</owner>
+  <summary>
+    Number of simultaneous inputs coming to the AudioRendererMixer rendering
+    audio with real time latency. The value is lifetime maximum logged on the
+    mixer destruction. It is useful for evaluating how mixing audio in renderer
+    reduces the number of output audio streams going from the renderer to the
+    browser.
+  </summary>
+</histogram>
+
+<histogram name="Media.Audio.Render.AudioMixing.LatencyMap" units="subsets">
+  <owner>olka@chromium.org</owner>
+  <summary>
+    Subset of audio output latencies encountered during the renderer lifetime.
+    Logged on the renderer destruction. The values are bitsets where each bit
+    represents corresponding latency according to AudioLatency::LatencyType.
+    Useful for understanding usecases for audio output mixing in renderer.
+  </summary>
+</histogram>
+
 <histogram name="Media.Audio.Render.FramesRequested" units="frames">
   <owner>tommi@chromium.org</owner>
   <summary>