Add IPC to allow gpu process to send message for console back to renderer

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 d5004bbaa79cc69154d25b02e61ebb5ab28d0e18..0d6849dacc56059d4401dfe40addcee76ad4426e 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -43,6 +43,7 @@ struct DisallowedFeatures {
 class GLES2Decoder : public CommonDecoder {
  public:
   typedef error::Error Error;
+  typedef base::Callback<void(int32 id, const std::string& msg)> MsgCallback;
 
   // Creates a decoder.
   static GLES2Decoder* Create(ContextGroup* group);
@@ -133,6 +134,9 @@ class GLES2Decoder : public CommonDecoder {
       int width,
       int height) = 0;
 
+  // A callback for messages from the decoder.
+  virtual void SetMsgCallback(const MsgCallback& callback) = 0;
+
  protected:
   GLES2Decoder();