Fix MSAA on windows

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 803b1210b8e55c96764869810a5ddc7a5e9130a3..ef7462b9067c460f87095d9b703fdb27c83d0064 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -471,7 +471,9 @@ void FeatureInfo::InitializeFeatures() {
     enable_texture_format_bgra8888 = true;
   }
 
-  if (extensions.Contains("GL_EXT_bgra")) {
+  // Only desktop GL and ANGLE guarantee that we can allocate a renderbuffer

[vmiura, 2015/02/25 00:44:13]

nit: Could you clarify the comment to say "Only desktop GL extension GL_EXT_bgra
or ANGLE guarantee..."

+  // with this format.
+  if (extensions.Contains("GL_EXT_bgra") || gl_version_info_->is_angle) {
     enable_render_buffer_bgra = true;
   }