Remove SK_OFFSETOF from SkTypes, clean up offsetof usage.

gyp/common_conditions.gypi

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
@@ skipping 210 matching lines @@
           '-Winit-self',
           '-Wpointer-arith',
           '-Wsign-compare',
 
           '-Wno-unused-parameter',
         ],
         'cflags_cc': [
           '-std=c++11',
           '-fno-rtti',
           '-Wnon-virtual-dtor',
-          '-Wno-invalid-offsetof',  # GCC <4.6 is old-school strict about what is POD.
         ],
         'conditions': [
           [ 'skia_fast', { 'cflags': [ '<@(skia_fast_flags)' ] }],
           [ 'skia_os != "chromeos"', {
             'conditions': [
               [ 'skia_arch_type == "x86_64" and not skia_android_framework', {
                 'cflags': [
                   '-m64',
                 ],
                 'ldflags': [
@@ skipping 249 matching lines @@
             }, {
               'MACOSX_DEPLOYMENT_TARGET': '<(skia_osx_deployment_target)',
             }],
           ],
           'CLANG_CXX_LANGUAGE_STANDARD':               'c++11',
           'GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS': 'YES',  # -mssse3
           'GCC_SYMBOLS_PRIVATE_EXTERN':                'NO',   # -fvisibility=hidden
           'GCC_INLINES_ARE_PRIVATE_EXTERN':            'NO',   # -fvisibility-inlines-hidden
           'GCC_CW_ASM_SYNTAX':                         'NO',   # remove -fasm-blocks
           'GCC_ENABLE_PASCAL_STRINGS':                 'NO',   # remove -mpascal-strings
-          'GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO':     'NO',   # -Wno-invalid-offsetof
           'WARNING_CFLAGS': [
             '-Wall',
             '-Wextra',
             '-Winit-self',
             '-Wpointer-arith',
             '-Wsign-compare',
 
             '-Wno-unused-parameter',
           ],
         },
@@ skipping 27 matching lines @@
             'defines': [ 'NDEBUG' ],
           },
         },
         'xcode_settings': {
           'ARCHS': ['armv7'],
           'CODE_SIGNING_REQUIRED': 'NO',
           'CODE_SIGN_IDENTITY[sdk=iphoneos*]': 'iPhone Developer: Google Development (3F4Y5873JF)',
           'IPHONEOS_DEPLOYMENT_TARGET': '<(ios_sdk_version)',
           'SDKROOT': 'iphoneos',
           'TARGETED_DEVICE_FAMILY': '1,2',
-          'GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO': 'NO',   # -Wno-invalid-offsetof
           'OTHER_CPLUSPLUSFLAGS': [
             '-std=c++0x',
             '-fvisibility=hidden',
             '-fvisibility-inlines-hidden',
           ],
           'GCC_THUMB_SUPPORT': 'NO',
         },
       },
     ],
 
@@ skipping 60 matching lines @@
     [ 'sknx_no_simd', {
       'defines': [ 'SKNX_NO_SIMD' ],
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }