gpu: Remove Echo and SwapCompletion GL interfacess

mojo/gles2/command_buffer_client_impl.cc

Index: mojo/gles2/command_buffer_client_impl.cc
diff --git a/mojo/gles2/command_buffer_client_impl.cc b/mojo/gles2/command_buffer_client_impl.cc
index 2d3387b35a84abb5d8f9591704ba18950f7936a9..5c317a0c40f443f8be136f25a4c619787f3cef82 100644
--- a/mojo/gles2/command_buffer_client_impl.cc
+++ b/mojo/gles2/command_buffer_client_impl.cc
@@ -241,10 +241,6 @@ void CommandBufferClientImpl::SetSurfaceVisible(bool visible) {
   NOTIMPLEMENTED();
 }
 
-void CommandBufferClientImpl::Echo(const base::Closure& callback) {
-  command_buffer_->Echo(callback);
-}
-
 uint32 CommandBufferClientImpl::CreateStreamTexture(uint32 texture_id) {
   // TODO(piman)
   NOTIMPLEMENTED();