Allow overriding debug optimization level on mac.

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.
 
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
     # code, as opposed to external code.  This variable is used to control
     # such things as the set of warnings to enable, and whether warnings are
     # treated as errors.
@@ skipping 156 matching lines @@
             'msvs_large_module_debug_link_mode%': '1',  # No
           },{
             'msvs_large_module_debug_link_mode%': '2',  # Yes
           }],
         ],
       }],
     ],
   },
   'target_defaults': {
     'variables': {
-      'mac_release_optimization%': '3'  # Use -O3 unless overridden
+      'mac_release_optimization%': '3', # Use -O3 unless overridden
+      'mac_debug_optimization%': '0'    # Use -O0 unless overridden
     },
     'conditions': [
       ['branding=="Chrome"', {
         'defines': ['GOOGLE_CHROME_BUILD'],
       }, {  # else: branding!="Chrome"
         'defines': ['CHROMIUM_BUILD'],
       }],
       ['toolkit_views==1', {
         'defines': ['TOOLKIT_VIEWS=1'],
       }],
@@ skipping 42 matching lines @@
     'default_configuration': 'Debug',
     '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': '0',  # -O0
+          'GCC_OPTIMIZATION_LEVEL': '<(mac_debug_optimization)',
         },
         'conditions': [
           [ 'OS=="win"', {
             'configuration_platform': 'Win32',
             'msvs_configuration_attributes': {
               'OutputDirectory': '$(SolutionDir)$(ConfigurationName)',
               'IntermediateDirectory': '$(OutDir)\\obj\\$(ProjectName)',
               'CharacterSet': '1',
             },
             'msvs_settings': {
@@ skipping 519 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }