Mac ÜC: Enable back-pressure for the browser compositor

cc/output/output_surface.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/output_surface.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 324 matching lines @@
   context_provider_->ContextGL()->BeginQueryEXT(GL_LATENCY_QUERY_CHROMIUM,
                                                 gpu_latency_query_id);
   context_provider_->ContextGL()->EndQueryEXT(GL_LATENCY_QUERY_CHROMIUM);
   pending_gpu_latency_query_ids_.push_back(gpu_latency_query_id);
 #endif
 }
 
 void OutputSurface::PostSwapBuffersComplete() {
   base::MessageLoop::current()->PostTask(
       FROM_HERE,
-      base::Bind(&OutputSurface::OnSwapBuffersComplete,
+      base::Bind(&OutputSurface::DoOnSwapBuffersComplete,

[danakj, 2014/06/12 01:16:51]

Does virtual method in a posttask not do what you'd expect it to do, or why do
you need this indirection through DoOnSwapBuffersComplete, and not just bind
OnSwapBuffersComplete here directly?

[ccameron, 2014/06/12 01:28:25]

I was under the impression that a virtual method sent to posttask doesn't work
(well, it calls the precise method listed, not the derived class method).

But... I just tested this empirically, and it totally works! Huh! I wonder how
that's implemented...

                  weak_ptr_factory_.GetWeakPtr()));
 }
 
+void OutputSurface::DoOnSwapBuffersComplete() {
+  OnSwapBuffersComplete();
+}
+
 // We don't post tasks bound to the client directly since they might run
 // after the OutputSurface has been destroyed.
 void OutputSurface::OnSwapBuffersComplete() {
   client_->DidSwapBuffersComplete();
 }
 
 void OutputSurface::SetMemoryPolicy(const ManagedMemoryPolicy& policy) {
   TRACE_EVENT1("cc", "OutputSurface::SetMemoryPolicy",
                "bytes_limit_when_visible", policy.bytes_limit_when_visible);
   // Just ignore the memory manager when it says to set the limit to zero
   // bytes. This will happen when the memory manager thinks that the renderer
   // is not visible (which the renderer knows better).
   if (policy.bytes_limit_when_visible)
     client_->SetMemoryPolicy(policy);
 }
 
 }  // namespace cc