Fix TexImage2D clearing too agressively

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 302a3555e6241c88f733ce9551f9d2abc1cf08f0..8da35283cda3ad688391b9d3f6ac227bf4bd480e 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -145,12 +145,18 @@ class GLES2Decoder : public CommonDecoder {
   // A callback for messages from the decoder.
   virtual void SetMsgCallback(const MsgCallback& callback) = 0;
 
+  static bool IsAngle();
+
+  // Used for testing only
+  static void set_testing_force_is_angle(bool force);
+
  protected:
   GLES2Decoder();
 
  private:
   bool debug_;
   bool log_commands_;
+  static bool testing_force_is_angle_;
 
   DISALLOW_COPY_AND_ASSIGN(GLES2Decoder);
 };