gn win: Don't add linux-style cflags

media/base/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/ui.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//media/media_options.gni")
 
@@ skipping 334 matching lines @@
 
   if (is_android) {
     deps += [ "//ui/gl"]
   }
 }
 
 if (cpu_arch == "x86" || cpu_arch == "x64") {
   source_set("media_mmx") {
     sources = [ "simd/filter_yuv_mmx.cc" ]
     configs += [ "//media:media_config" ]
-    cflags = [ "-mmmx" ]
+    if (!is_win) {
+      cflags = [ "-mmmx" ]

[scottmg, 2014/08/13 23:25:35]

This is a bit tricky, 'cflags' is ignored in gyp on windows so there's likely
other places that will do incorrect conversions like this from .gyp files.

[DaleCurtis, 2014/08/14 00:23:26]

Does msvc require a similar setting?

+    }
   }
 
   source_set("media_sse2") {
     sources = [
       "simd/convert_rgb_to_yuv_sse2.cc",
       "simd/convert_rgb_to_yuv_ssse3.cc",
       "simd/filter_yuv_sse2.cc",
     ]
     configs += [ "//media:media_config" ]
-    cflags = [ "-msse2" ]
+    if (!is_win) {
+      cflags = [ "-msse2" ]
+    }
   }
 
   import("//third_party/yasm/yasm_assemble.gni")
   yasm_assemble("media_yasm") {
     sources = [
       "simd/convert_rgb_to_yuv_ssse3.asm",
       "simd/convert_yuv_to_rgb_mmx.asm",
       "simd/convert_yuv_to_rgb_sse.asm",
       "simd/convert_yuva_to_argb_mmx.asm",
       "simd/empty_register_state_mmx.asm",
@@ skipping 41 matching lines @@
       if (is_posix) {
         yasm_flags += [ "-DELF" ]
         if (cpu_arch == "x64") {
         # TODO(ajwong): Why isn't this true in mac?
           yasm_flags += [ "-DPIC" ]
         }
       }
     }
   }
 }