Count usage of mediastream audio and video constraints.

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 ac15d0d3e8d199d3a9d58b18ff8832ef0c3a7a99..58970ad96c290340654e69d80764e825eb1a606d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -95396,6 +95396,52 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1915" label="CanRequestURLNonHTTPContainingNewline"/>
   <int value="1916" label="GetGamepads"/>
   <int value="1917" label="V8SVGPathElement_GetPathSegAtLength_Method"/>
+  <int value="1918" label="MediaStreamConstraintsAudio"/>
+  <int value="1919" label="MediaStreamConstraintsAudioUnconstrained"/>
+  <int value="1920" label="MediaStreamConstraintsVideo"/>
+  <int value="1921" label="MediaStreamConstraintsVideoUnconstrained"/>
+  <int value="1922" label="MediaStreamConstraintsWidth"/>
+  <int value="1923" label="MediaStreamConstraintsHeight"/>
+  <int value="1924" label="MediaStreamConstraintsAspectRatio"/>
+  <int value="1925" label="MediaStreamConstraintsFrameRate"/>
+  <int value="1926" label="MediaStreamConstraintsFacingMode"/>
+  <int value="1927" label="MediaStreamConstraintsVolume"/>
+  <int value="1928" label="MediaStreamConstraintsSampleRate"/>
+  <int value="1929" label="MediaStreamConstraintsSampleSize"/>
+  <int value="1930" label="MediaStreamConstraintsEchoCancellation"/>
+  <int value="1931" label="MediaStreamConstraintsLatency"/>
+  <int value="1932" label="MediaStreamConstraintsChannelCount"/>
+  <int value="1933" label="MediaStreamConstraintsDeviceIdAudio"/>
+  <int value="1934" label="MediaStreamConstraintsDeviceIdVideo"/>
+  <int value="1935" label="MediaStreamConstraintsDisableLocalEcho"/>
+  <int value="1936" label="MediaStreamConstraintsGroupIdAudio"/>
+  <int value="1937" label="MediaStreamConstraintsGroupIdVideo"/>
+  <int value="1938" label="MediaStreamConstraintsVideoKind"/>
+  <int value="1939" label="MediaStreamConstraintsDepthNear"/>
+  <int value="1940" label="MediaStreamConstraintsDepthFar"/>
+  <int value="1941" label="MediaStreamConstraintsFocalLengthX"/>
+  <int value="1942" label="MediaStreamConstraintsFocalLengthY"/>
+  <int value="1943" label="MediaStreamConstraintsMediaStreamSourceAudio"/>
+  <int value="1944" label="MediaStreamConstraintsMediaStreamSourceVideo"/>
+  <int value="1945" label="MediaStreamConstraintsRenderToAssociatedSink"/>
+  <int value="1946" label="MediaStreamConstraintsHotwordEnabled"/>
+  <int value="1947" label="MediaStreamConstraintsGoogEchoCancellation"/>
+  <int value="1948"
+      label="MediaStreamConstraintsGoogExperimentalEchoCancellation"/>
+  <int value="1949" label="MediaStreamConstraintsGoogAutoGainControl"/>
+  <int value="1950"
+      label="MediaStreamConstraintsGoogExperimentalAutoGainControl"/>
+  <int value="1951" label="MediaStreamConstraintsGoogNoiseSuppression"/>
+  <int value="1952" label="MediaStreamConstraintsGoogHighpassFilter"/>
+  <int value="1953" label="MediaStreamConstraintsGoogTypingNoiseDetection"/>
+  <int value="1954"
+      label="MediaStreamConstraintsGoogExperimentalNoiseSuppression"/>
+  <int value="1955" label="MediaStreamConstraintsGoogBeamforming"/>
+  <int value="1956" label="MediaStreamConstraintsGoogArrayGeometry"/>
+  <int value="1957" label="MediaStreamConstraintsGoogAudioMirroring"/>
+  <int value="1958" label="MediaStreamConstraintsGoogDAEchoCancellation"/>
+  <int value="1959" label="MediaStreamConstraintsGoogNoiseReduction"/>
+  <int value="1960" label="MediaStreamConstraintsGoogPowerLineFrequency"/>
 </enum>
 
 <enum name="FetchRequestMode" type="int">