Split Media.Controls.Show in .Video and .Audio.

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 30a8084131fb2fbd27051b1378ff1414c522826a..1bf539dd220f8d6033ef20a794512009ed0d3776 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -20695,10 +20695,31 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Media.Controls.Show" enum="MediaControlsShowReason">
+  <obsolete>
+    Deprecated May 19 2016 in favor of Media.Controls.Show.{Audio,Video}
+  </obsolete>
+  <owner>mlamouri@chromium.org</owner>
+  <summary>
+    Record whether the default media controls were shown and why every time they
+    could be shown.
+  </summary>
+</histogram>
+
+<histogram name="Media.Controls.Show.Audio" enum="MediaControlsShowReason">
+  <owner>mlamouri@chromium.org</owner>
+  <summary>
+    Record whether the default media controls of an audio element were shown and
+    why every time they could be shown. Note that audio elements that were not
+    insterted to the DOM and do not have a controls attribute are not taken into
+    account.
+  </summary>
+</histogram>
+
+<histogram name="Media.Controls.Show.Video" enum="MediaControlsShowReason">
   <owner>mlamouri@chromium.org</owner>
   <summary>
-    Record whether the default media controls where shown and why every time
-    they could be shown.
+    Record whether the default media controls of a video element were shown and
+    why every time they could be shown.
   </summary>
 </histogram>