Add UMA stats to record when DLLs are successfully blocked in the Browser.

PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 876 matching lines @@
 
 
 def _CheckSpamLogging(input_api, output_api):
   file_inclusion_pattern = r'.+%s' % _IMPLEMENTATION_EXTENSIONS
   black_list = (_EXCLUDED_PATHS +
                 _TEST_CODE_EXCLUDED_PATHS +
                 input_api.DEFAULT_BLACK_LIST +
                 (r"^base[\\\/]logging\.h$",
                  r"^base[\\\/]logging\.cc$",
                  r"^cloud_print[\\\/]",
+                 r"^chrome_elf[\\\/]dll_hash[\\\/]dll_hash_main\.cc$",
                  r"^chrome[\\\/]app[\\\/]chrome_main_delegate\.cc$",
                  r"^chrome[\\\/]browser[\\\/]chrome_browser_main\.cc$",
                  r"^chrome[\\\/]browser[\\\/]ui[\\\/]startup[\\\/]"
                      r"startup_browser_creator\.cc$",
                  r"^chrome[\\\/]installer[\\\/]setup[\\\/].*",
                  r"^chrome[\\\/]renderer[\\\/]extensions[\\\/]"
                      r"logging_native_handler\.cc$",
                  r"^content[\\\/]common[\\\/]gpu[\\\/]client[\\\/]"
                      r"gl_helper_benchmark\.cc$",
                  r"^remoting[\\\/]base[\\\/]logging\.h$",
@@ skipping 514 matching lines @@
     trybots.extend(GetDefaultTryConfigs(['cros_x86']))
 
   # The AOSP bot doesn't build the chrome/ layer, so ignore any changes to it
   # unless they're .gyp(i) files as changes to those files can break the gyp
   # step on that bot.
   if (not all(re.search('^chrome', f) for f in files) or
       any(re.search('\.gypi?$', f) for f in files)):
     trybots.extend(GetDefaultTryConfigs(['android_aosp']))
 
   return trybots