Add MGLEcho

mojo/gles2/control_thunks_impl.h

Index: mojo/gles2/control_thunks_impl.h
diff --git a/mojo/gles2/control_thunks_impl.h b/mojo/gles2/control_thunks_impl.h
index 13a794b98c9076046f3732232ddbb2f2db44916d..541ae34b6420829de49495a3c679f8952b3a4eed 100644
--- a/mojo/gles2/control_thunks_impl.h
+++ b/mojo/gles2/control_thunks_impl.h
@@ -10,6 +10,7 @@
 #include "gpu/GLES2/gl2extchromium.h"
 #include "mojo/gles2/gles2_context.h"
 #include "mojo/public/c/gpu/MGL/mgl.h"
+#include "mojo/public/c/gpu/MGL/mgl_echo.h"
 #include "mojo/public/c/gpu/MGL/mgl_signal_sync_point.h"
 
 namespace gpu {
@@ -48,6 +49,8 @@ class ControlThunksImpl {
 
   void* GetGLES2Interface(MGLContext context);
 
+  void Echo(MGLEchoCallback callback, void* closure);
+
   void SignalSyncPoint(uint32_t sync_point,
                        MGLSignalSyncPointCallback callback,
                        void* closure);