Connect up --disable-gl-multisampling to command buffer

gpu/command_buffer/service/gles2_cmd_decoder.h

Index: gpu/command_buffer/service/gles2_cmd_decoder.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.h b/gpu/command_buffer/service/gles2_cmd_decoder.h
index 88d189275f467d713008e440c48c954ed6b038d3..92d5300af94f93f982e357419407cded966a10d8 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -25,6 +25,10 @@ namespace gles2 {
 class ContextGroup;
 class GLES2Util;
 
+struct DisallowedExtensions {
+  bool multisampling;
+};
+
 // This class implements the AsyncAPIInterface interface, decoding GLES2
 // commands and calling GL.
 class GLES2Decoder : public CommonDecoder {
@@ -61,6 +65,7 @@ class GLES2Decoder : public CommonDecoder {
   //   true if successful.
   virtual bool Initialize(gfx::GLContext* context,
                           const gfx::Size& size,
+                          const DisallowedExtensions& disallowed_extensions,
                           const char* allowed_extensions,
                           const std::vector<int32>& attribs,
                           GLES2Decoder* parent,