Trim down OSX GYP rules. Same effect, shorter.

gyp/common_conditions.gypi

 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
     'SK_SUPPORT_GPU=<(skia_gpu)',
     'SK_SUPPORT_OPENCL=<(skia_opencl)',
     'SK_FORCE_DISTANCEFIELD_FONTS=<(skia_force_distancefield_fonts)',
   ],
   'conditions' : [
@@ skipping 461 matching lines @@
           }],
           [ 'skia_keep_frame_pointer', {
             'cflags': [ '-fno-omit-frame-pointer' ],
           }],
         ],
       },
     ],
 
     [ 'skia_os == "mac"',
       {
-        'defines': [
-          'SK_BUILD_FOR_MAC',
-        ],
-        'conditions' : [
-          [ 'skia_arch_width == 64', {
-            'xcode_settings': {
-              'ARCHS': ['x86_64'],
-            },
-          }],
-          [ 'skia_arch_width == 32', {
-            'xcode_settings': {
-              'ARCHS': ['i386'],
-            },
-          }],
-          [ 'skia_warnings_as_errors', {
-            'xcode_settings': {
-              'OTHER_CPLUSPLUSFLAGS': [
-                '-Werror',
-                '-Wall',
-                '-Wextra',
-                '-Wno-unused-parameter',
-                '-Wno-uninitialized',  # Disabled because we think GCC 4.2 is bad at this.
-              ],
-            },
-          }],
-        ],
+        'defines': [ 'SK_BUILD_FOR_MAC' ],
         'configurations': {
           'Coverage': {
             'xcode_settings': {
                'GCC_OPTIMIZATION_LEVEL': '0',
                'GCC_GENERATE_TEST_COVERAGE_FILES': 'YES',
                'GCC_INSTRUMENT_PROGRAM_FLOW_ARCS' : 'YES',
             },
           },
           'Debug': {
-            'xcode_settings': {
-              'GCC_OPTIMIZATION_LEVEL': '0',
-            },
+            'xcode_settings': { 'GCC_OPTIMIZATION_LEVEL': '0' },
           },
           'Release': {
-            'xcode_settings': {
-              'GCC_OPTIMIZATION_LEVEL': '<(skia_release_optimization_level)',
-            },
+            'xcode_settings': { 'GCC_OPTIMIZATION_LEVEL': '<(skia_release_optimization_level)', },
             'defines': [ 'NDEBUG' ],
           },
         },
         'xcode_settings': {
-          'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO',
           'conditions': [
+            [ 'skia_warnings_as_errors', { 'GCC_TREAT_WARNINGS_AS_ERRORS': 'YES' }],
+            [ 'skia_arch_width == 32', { 'ARCHS': ['i386']   }],
+            [ 'skia_arch_width == 64', { 'ARCHS': ['x86_64'] }],
             [ 'skia_osx_deployment_target==""', {
-              'MACOSX_DEPLOYMENT_TARGET': '10.6', # -mmacos-version-min, passed in environment to ld.
+              'MACOSX_DEPLOYMENT_TARGET': '10.6', # -mmacos-version-min, passed in env to ld.
             }, {
               'MACOSX_DEPLOYMENT_TARGET': '<(skia_osx_deployment_target)',
             }],
           ],
-# trying to get this to work, but it needs clang I think...
-#          'WARNING_CFLAGS': '-Wexit-time-destructors',
-          'CLANG_WARN_CXX0X_EXTENSIONS': 'NO',
-          'GCC_WARN_64_TO_32_BIT_CONVERSION': 'YES',
-          'GCC_WARN_ABOUT_DEPRECATED_FUNCTIONS': 'YES',
-          'GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO': 'YES',
-          'GCC_WARN_ABOUT_MISSING_NEWLINE': 'YES',
-          'GCC_WARN_ABOUT_MISSING_PROTOTYPES': 'YES',
-          'GCC_WARN_ABOUT_POINTER_SIGNEDNESS': 'YES',
-          'GCC_WARN_ABOUT_RETURN_TYPE': 'YES',
-          'GCC_WARN_ALLOW_INCOMPLETE_PROTOCOL': 'YES',
-          'GCC_WARN_INITIALIZER_NOT_FULLY_BRACKETED': 'YES',
-          'GCC_WARN_MISSING_PARENTHESES': 'YES',
-          'GCC_WARN_PROTOTYPE_CONVERSION': 'YES',
-          'GCC_WARN_SIGN_COMPARE': 'YES',
-          'GCC_WARN_TYPECHECK_CALLS_TO_PRINTF': 'YES',
-          'GCC_WARN_UNKNOWN_PRAGMAS': 'YES',
-          'GCC_WARN_UNUSED_FUNCTION': 'YES',
-          'GCC_WARN_UNUSED_LABEL': 'YES',
-          'GCC_WARN_UNUSED_VALUE': 'YES',
-          'GCC_WARN_UNUSED_VARIABLE': 'YES',
-          'OTHER_CPLUSPLUSFLAGS': [
-            '-mssse3',
-            '-fvisibility=hidden',
-            '-fvisibility-inlines-hidden',
+          'GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS': 'YES',  # -mssse3
+          'GCC_SYMBOLS_PRIVATE_EXTERN':                'NO',   # -fvisibility=hidden
+          'GCC_INLINES_ARE_PRIVATE_EXTERN':            'NO',   # -fvisibility-inlines-hidden
+          'WARNING_CFLAGS': [
+            '-Wall',
+            '-Wextra',
+            '-Wno-unused-parameter',
+            '-Wno-uninitialized',  # Disabled because we think GCC 4.2 is bad at this.
           ],
         },
       },
     ],
 
     [ 'skia_os == "ios"',
       {
         'defines': [
           'SK_BUILD_FOR_IOS',
         ],
@@ skipping 106 matching lines @@
     [ 'skia_is_bot', {
       'defines': [ 'SK_CRASH_HANDLER' ],
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }