When autoplaying muted video, record when unmute happen and the result.

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 48932868a0b3a43b13f7c5939e80ec455b39e470..52992955f0eab300b3655b6be281baa2ad99b538 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -22332,8 +22332,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Media.Video.Autoplay" enum="AutoplaySource">
-  <owner>mlamouri@chromium.org</owner>
   <owner>avayvod@chromium.org</owner>
+  <owner>mlamouri@chromium.org</owner>
   <owner>zqzhang@chromium.org</owner>
   <summary>
     Records the autoplay source of videos. This includes
@@ -22342,12 +22342,21 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Media.Video.Autoplay.Muted" enum="AutoplaySource">
-  <owner>mlamouri@chromium.org</owner>
   <owner>avayvod@chromium.org</owner>
+  <owner>mlamouri@chromium.org</owner>
   <owner>zqzhang@chromium.org</owner>
   <summary>Records the autoplay source of muted videos.</summary>
 </histogram>
 
+<histogram name="Media.Video.Autoplay.Muted.UnmuteAction" enum="BooleanSuccess">
+  <owner>avayvod@chromium.org</owner>
+  <owner>mlamouri@chromium.org</owner>
+  <owner>zqzhang@chromium.org</owner>
+  <summary>
+    Status of the unmute action on a video that autoplayed because it was muted.
+  </summary>
+</histogram>
+
 <histogram name="Media.VideoCapture.AspectRatio" units="%">
   <owner>mcasas@chromium.org</owner>
   <summary>