Add options for audio/video autoplay to chrome://settings/content.

tools/metrics/actions/actions.xml

 <!--
 Copyright 2014 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <!--
 This file is a comprehensive list of Chrome user actions along with the owner
 and description for each user action. A user action should be tied to an actual
 action taken by a user. It should be logged immediatly after a user takes the
@@ skipping 9347 matching lines @@
   <description>Please enter the description of this user action.</description>
 </action>
 
 <action name="Options_DefaultMIDISysExSettingChanged">
   <owner>toyoshim@chromium.org</owner>
   <description>
     Triggers when the default decision for Midi SysEx permissions is changed.
   </description>
 </action>
 
+<action name="Options_DefaultMediaAutoplaySettingChanged">
+  <owner>dalecurtis@chromium.org</owner>
+  <description>
+    Triggers when the default decision for media autoplay permission is changed.
+  </description>
+</action>
+
 <action name="Options_DefaultMediaStreamCameraSettingChanged">
   <owner>msramek@chromium.org</owner>
   <description>
     Recorded when the default value for the camera content setting is changed by
     the user.
   </description>
 </action>
 
 <action name="Options_DefaultMediaStreamMicSettingChanged">
   <owner>msramek@chromium.org</owner>
@@ skipping 3677 matching lines @@
 <action name="webapps.AddShortcut.Manifest">
   <owner>mlamouri@chromium.org</owner>
   <description>
     Shortcut added to the homescreen with a valid Manifest. This action will be
     recorded in addition to AppShortcut, AppShortcutApple and Bookmark actions
     to keep a trend of whether the webapp also add meta tags.
   </description>
 </action>
 
 </actions>