SSE2 everywhere.

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' : [
     [ 'skia_arch_type == "arm64"', {
       'cflags': [
         '-ffp-contract=off',
       ],
     }],
 
+    # As of M35, Chrome requires SSE2 on x86 (and SSSE3 on Mac).
+    [ 'skia_arch_type == "x86"', {
+      'cflags': [
+        '-msse2',
+        '-mfpmath=sse',
+      ],
+    }],
+
     [ 'skia_os == "win"',
       {
         'defines': [
           'SK_BUILD_FOR_WIN32',
           '_CRT_SECURE_NO_WARNINGS',
           'GR_GL_FUNCTION_TYPE=__stdcall',
         ],
         'msvs_disabled_warnings': [
             4345,  # This is an FYI about a behavior change from long ago.  Chrome stifles it too.
         ],
@@ skipping 616 matching lines @@
         'SK_BUILD_JSON_WRITER',
       ]
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }