Enable MMX for Chrome

BUG=41259,19113
TEST=build code that uses mmx intrinsics.

Review URL: http://codereview.chromium.org/1604030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@44325 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -405,7 +405,7 @@
               'GCC_GENERATE_TEST_COVERAGE_FILES': 'YES',  # -ftest-coverage
             },
             # Add -lgcov for types executable, shared_library, and
-            # loadable_module; not for static_library.  
+            # loadable_module; not for static_library.
             # This is a delayed conditional.
             'target_conditions': [
               ['_type!="static_library"', {
@@ -890,8 +890,11 @@
                 ],
               }],
             ],
+            # -mmmx allows mmintrin.h to be used for mmx intrinsics.
+            # video playback is mmx and sse2 optimized.
             'cflags': [
               '-m32',
+              '-mmmx',
             ],
             'ldflags': [
               '-m32',