Update histograms.xml for recent BadMessage values.

content/browser/bad_message.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_BAD_MESSAGE_H_
 #define CONTENT_BROWSER_BAD_MESSAGE_H_
 
 namespace content {
 class RenderProcessHost;
 
 namespace bad_message {
 
 // The browser process often chooses to terminate a renderer if it receives
 // a bad IPC message. The reasons are tracked for metrics.
 //
 // Content embedders should implement their own bad message statistics but
 // should use similar histogram names to make analysis easier.
 //
 // NOTE: Do not remove or reorder elements in this list. Add new entries at the
 // end. Items may be renamed but do not change the values. We rely on the enum
-// values in histograms.
+// values in histograms. Also update histograms.xml with any new values.
 enum BadMessageReason {
   NC_IN_PAGE_NAVIGATION = 0,

[Mark P, 2015/05/11 22:19:01]

It's good practice to explicitly do = 0, = 1, etc. all the way down.  This way
if someone inadvertently removes an item from the enum, it doesn't screw
everything up.  (That said, you still shouldn't remove items.)

ditto on other file

[Charlie Reis, 2015/05/11 22:37:57]

Done.

   RFH_CAN_COMMIT_URL_BLOCKED,
   RFH_CAN_ACCESS_FILES_OF_PAGE_STATE,
   RFH_SANDBOX_FLAGS,
   RFH_NO_PROXY_TO_PARENT,
   RPH_DESERIALIZATION_FAILED,
   RVH_CAN_ACCESS_FILES_OF_PAGE_STATE,
   RVH_FILE_CHOOSER_PATH,
   RWH_SYNTHETIC_GESTURE,
   RWH_FOCUS,
   RWH_BLUR,
@@ skipping 14 matching lines @@
 
 // Called when the browser receives a bad IPC message from a renderer process.
 // Logs the event, records a histogram metric for the |reason|, and terminates
 // the process for |host|.
 void ReceivedBadMessage(RenderProcessHost* host, BadMessageReason reason);
 
 }  // namespace bad_message
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BAD_MESSAGE_H_