Add command buffer support for GL_RGB CHROMIUM image emulation.

gpu/command_buffer/service/framebuffer_manager.h

Index: gpu/command_buffer/service/framebuffer_manager.h
diff --git a/gpu/command_buffer/service/framebuffer_manager.h b/gpu/command_buffer/service/framebuffer_manager.h
index 67257dafd25d4526363dd4a5bb12493d9140d338..b6a2af30cdd63d51de4b5f1d2d79b0c6c085ff17 100644
--- a/gpu/command_buffer/service/framebuffer_manager.h
+++ b/gpu/command_buffer/service/framebuffer_manager.h
@@ -62,6 +62,7 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
     virtual void AddToSignature(
         TextureManager* texture_manager, std::string* signature) const = 0;
     virtual bool FormsFeedbackLoop(TextureRef* texture, GLint level) const = 0;
+    virtual bool EmulatingRGB() const = 0;
 
    protected:
     friend class base::RefCounted<Attachment>;