Adding presubmit check for WeakPtrFactory in the code

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 1264 matching lines @@
   for fpath in input_api.AffectedFiles(file_filter=file_filter):
     for lnum, line in fpath.ChangedContents():
       for (deprecated, replacement) in _DEPRECATED_JS:
         if deprecated in line:
           results.append(output_api.PresubmitError(
               "%s:%d: Use of deprecated JS %s, use %s instead" %
               (fpath.LocalPath(), lnum, deprecated, replacement)))
   return results
 
 
+def _CheckForWeakPtrOrder(input_api, output_api):
+  """Check for weakptrfactory order in .h files using ChangedContents."""
+  problems = []
+  warnings = []
+  for f in input_api.AffectedFiles():
+    if not f.LocalPath().endswith(('.cc', '.cpp', '.h', '.mm')):
+      continue
+    contents = f.NewContents()
+    weak_ptr_flag = False
+    change_line_num = 0
+    for line_num, line in f.ChangedContents():
+      change_line_num = line_num
+      break
+    curr_line = 0
+    change_flag = False
+    for line in contents:
+      curr_line += 1
+      if (curr_line != change_line_num) and (change_flag != True):
+        continue
+      else:
+        change_flag = True
+      if 'base::WeakPtrFactory' in line:
+        weak_ptr_flag = True
+        continue
+      if weak_ptr_flag == True:
+        #Checking for commented line
+        strip_line = line.strip()
+        if strip_line.startswith('//'):
+          continue
+        #Check for emptyline for skipping
+        if (len(line.strip()) == 0):
+          continue
+        #Check for valid attributes after the WeakPtrFactory pointer
+        if input_api.re.search(r'(};|\bDISALLOW_COPY_AND_ASSIGN\b)', line):
+          break
+        else:
+          weak_ptr_flag = False
+          problems.append('    %s:%d' % (f.LocalPath(), line_num))
+          break
+
+  if not problems:
+    return []
+  return [output_api.PresubmitError(
+    'Member variables should appear before the WeakPtrFactory, to ensure '
+    'that any WeakPtrs to Controller are \ninvalidated before its members '
+    'variable\'s destructors are executed, rendering them invalid.',
+    problems)]
+
+
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
   results = []
   results.extend(input_api.canned_checks.PanProjectChecks(
       input_api, output_api,
       excluded_paths=_EXCLUDED_PATHS + _TESTRUNNER_PATHS))
   results.extend(_CheckAuthorizedAuthor(input_api, output_api))
   results.extend(
       _CheckNoProductionCodeUsingTestOnlyFunctions(input_api, output_api))
   results.extend(_CheckNoIOStreamInHeaders(input_api, output_api))
@@ skipping 23 matching lines @@
           source_file_filter=lambda x: x.LocalPath().endswith('.grd')))
   results.extend(_CheckSpamLogging(input_api, output_api))
   results.extend(_CheckForAnonymousVariables(input_api, output_api))
   results.extend(_CheckCygwinShell(input_api, output_api))
   results.extend(_CheckUserActionUpdate(input_api, output_api))
   results.extend(_CheckNoDeprecatedCSS(input_api, output_api))
   results.extend(_CheckNoDeprecatedJS(input_api, output_api))
   results.extend(_CheckParseErrors(input_api, output_api))
   results.extend(_CheckForIPCRules(input_api, output_api))
 
+  results.extend(_CheckForWeakPtrOrder(input_api, output_api))
   if any('PRESUBMIT.py' == f.LocalPath() for f in input_api.AffectedFiles()):
     results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
         input_api, output_api,
         input_api.PresubmitLocalPath(),
         whitelist=[r'^PRESUBMIT_test\.py$']))
   return results
 
 
 def _CheckAuthorizedAuthor(input_api, output_api):
   """For non-googler/chromites committers, verify the author's email address is
@@ skipping 401 matching lines @@
     builders.extend(['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)):
     builders.extend(['android_aosp'])
 
   return GetDefaultTryConfigs(builders)