gpu: Remove Echo and SwapCompletion GL interfacess

cc/output/output_surface.cc

Index: cc/output/output_surface.cc
diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index 2b6b7829999ef01c60648b6de7ed9acb4dce1fe7..2c251eb9c44c748320d60c820344c8ca1d39ad8c 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -177,9 +177,6 @@ void OutputSurface::SetUpContext3d() {
   context_provider_->SetLostContextCallback(
       base::Bind(&OutputSurface::DidLoseOutputSurface,
                  base::Unretained(this)));
-  context_provider_->ContextSupport()->SetSwapBuffersCompleteCallback(
-      base::Bind(&OutputSurface::OnSwapBuffersComplete,
-                 base::Unretained(this)));
   context_provider_->SetMemoryPolicyChangedCallback(
       base::Bind(&OutputSurface::SetMemoryPolicy,
                  base::Unretained(this)));
@@ -207,8 +204,6 @@ void OutputSurface::ResetContext3d() {
         ContextProvider::LostContextCallback());
     context_provider_->SetMemoryPolicyChangedCallback(
         ContextProvider::MemoryPolicyChangedCallback());
-    if (gpu::ContextSupport* support = context_provider_->ContextSupport())
-      support->SetSwapBuffersCompleteCallback(base::Closure());
   }
   context_provider_ = NULL;
 }
@@ -266,6 +261,12 @@ void OutputSurface::SwapBuffers(CompositorFrame* frame) {
     context_provider_->ContextSupport()->PartialSwapBuffers(
         frame->gl_frame_data->sub_buffer_rect);
   }
+  uint32_t sync_point =
+      context_provider_->ContextGL()->InsertSyncPointCHROMIUM();
+  context_provider_->ContextSupport()->SignalSyncPoint(
+      sync_point,
+      base::Bind(&OutputSurface::OnSwapBuffersComplete,
+                 weak_ptr_factory_.GetWeakPtr()));
 
   client_->DidSwapBuffers();
 }