Also check .cpp files for include rules violations

tools/checkdeps/cpp_checker.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.
 
 """Checks C++ and Objective-C files for illegal includes."""
 
 import codecs
 import os
 import re
 
 import results
 from rules import Rule, MessageRule
 
 
 class CppChecker(object):
 
   EXTENSIONS = [
       '.h',
       '.cc',
+      '.cpp',
       '.m',
       '.mm',
   ]
 
   # The maximum number of non-include lines we can see before giving up.
   _MAX_UNINTERESTING_LINES = 50
 
   # The maximum line length, this is to be efficient in the case of very long
   # lines (which can't be #includes).
   _MAX_LINE_LENGTH = 128
@@ skipping 73 matching lines @@
           dependee_status.AddViolation(violation)
 
     return dependee_status
 
   @staticmethod
   def IsCppFile(file_path):
     """Returns True iff the given path ends in one of the extensions
     handled by this checker.
     """
     return os.path.splitext(file_path)[1] in CppChecker.EXTENSIONS