Back out r29591 (-fstack-protector) because it may have caused Valgrind test failures

build/common.gypi

 # Copyright (c) 2009 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
@@ skipping 336 matching lines @@
     'configurations': {
        # VCLinkerTool LinkIncremental values below:
        #   0 == default
        #   1 == /INCREMENTAL:NO
        #   2 == /INCREMENTAL
        # Debug links incremental, Release does not.
       'Debug': {
         'xcode_settings': {
           'COPY_PHASE_STRIP': 'NO',
           'GCC_OPTIMIZATION_LEVEL': '<(mac_debug_optimization)',
-          'OTHER_CFLAGS': [
-            '-fstack-protector',
-            '-fstack-protector-all',
-            '<@(debug_extra_cflags)',
-          ],
+          'OTHER_CFLAGS': [ '<@(debug_extra_cflags)', ],
         },
         'conditions': [
           [ 'OS=="win"', {
             'configuration_platform': 'Win32',
             'msvs_configuration_attributes': {
               'OutputDirectory': '$(SolutionDir)$(ConfigurationName)',
               'IntermediateDirectory': '$(OutDir)\\obj\\$(ProjectName)',
               'CharacterSet': '1',
             },
             'msvs_settings': {
@@ skipping 568 matching lines @@
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
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