Added PPAPI win32k lockdown options to chrome://flags.

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 158 matching lines @@
 <action name="AboutFlags_enable-nacl-exception-handling">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <description>Please enter the description of this user action.</description>
 </action>
 
 <action name="AboutFlags_enable-pnacl">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <description>Please enter the description of this user action.</description>
 </action>
 
+<action name="AboutFlags_enable-ppapi-win32k-lockdown">
+  <owner>wfh@chromium.org</owner>
+  <owner>forshaw@chromium.org</owner>
+  <description>
+    User enabled flag that specifies which PPAPI plugins are run within the
+    win32k lockdown sandbox policy on Windows.
+  </description>
+</action>

[Ilya Sherman, 2015/09/30 04:13:37]

Hmm, I don't remember: Is this entry automatically added?  If so, LGTM.  If not,
do you really need this as both an action and in the histogram?

+
 <action name="AboutFlags_enable-smooth-scrolling">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <description>Please enter the description of this user action.</description>
 </action>
 
 <action name="AboutFlags_enable-website-settings">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <description>Please enter the description of this user action.</description>
 </action>
 
@@ skipping 12662 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>