gpu: Remove Echo and SwapCompletion GL interfacess

gpu/command_buffer/client/context_support.h

Index: gpu/command_buffer/client/context_support.h
diff --git a/gpu/command_buffer/client/context_support.h b/gpu/command_buffer/client/context_support.h
index f8ff15effe89dae551b1bb24bba071ec7700316e..7046d9674b35e6308f07b0c39f9c1d5156548aea 100644
--- a/gpu/command_buffer/client/context_support.h
+++ b/gpu/command_buffer/client/context_support.h
@@ -25,12 +25,6 @@ class ContextSupport {
   // Clients aren't expected to draw to an invisible surface.
   virtual void SetSurfaceVisible(bool visible) = 0;
 
-  virtual void Swap() = 0;
-  virtual void PartialSwapBuffers(const gfx::Rect& sub_buffer) = 0;
-
-  virtual void SetSwapBuffersCompleteCallback(
-      const base::Closure& callback) = 0;
-
   // Schedule a texture to be presented as an overlay synchronously with the
   // primary surface during the next buffer swap.
   // This method is not stateful and needs to be re-scheduled every frame.