Sync compositor: Ignore command buffer memory callback

content/common/gpu/client/context_provider_command_buffer.cc

Index: content/common/gpu/client/context_provider_command_buffer.cc
diff --git a/content/common/gpu/client/context_provider_command_buffer.cc b/content/common/gpu/client/context_provider_command_buffer.cc
index cb827258a5fdf8c271bc0d3eb73874d9a5bc7fe4..e4409285f7a08eb841bc9d679a5540fbb8394857 100644
--- a/content/common/gpu/client/context_provider_command_buffer.cc
+++ b/content/common/gpu/client/context_provider_command_buffer.cc
@@ -43,15 +43,19 @@ ContextProviderCommandBuffer::Create(
   if (!context3d)
     return NULL;
 
-  return new ContextProviderCommandBuffer(context3d.Pass(), type);
+  const bool enable_memory_allocation_callback = true;
+  return new ContextProviderCommandBuffer(context3d.Pass(), type,
+                                          enable_memory_allocation_callback);
 }
 
 ContextProviderCommandBuffer::ContextProviderCommandBuffer(
     scoped_ptr<WebGraphicsContext3DCommandBufferImpl> context3d,
-    CommandBufferContextType type)
+    CommandBufferContextType type,
+    bool enable_memory_allocation_callback)
     : context3d_(context3d.Pass()),
       context_type_(type),
       debug_name_(CommandBufferContextTypeToString(type)),
+      enable_memory_allocation_callback_(enable_memory_allocation_callback),
       destroyed_(false) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK(context3d_);
@@ -105,9 +109,12 @@ bool ContextProviderCommandBuffer::BindToCurrentThread() {
   context3d_->traceBeginCHROMIUM("gpu_toplevel", unique_context_name.c_str());
 
   lost_context_callback_proxy_.reset(new LostContextCallbackProxy(this));
-  context3d_->GetCommandBufferProxy()->SetMemoryAllocationChangedCallback(
-      base::Bind(&ContextProviderCommandBuffer::OnMemoryAllocationChanged,
-                 base::Unretained(this)));
+
+  if (enable_memory_allocation_callback_) {
+    context3d_->GetCommandBufferProxy()->SetMemoryAllocationChangedCallback(

[no sievers, 2015/08/05 22:50:32]

Wait, can you just move this code to SetMemoryPolicyChangedCallback() and then
override that in your subclass to do nothing? :)

[boliu, 2015/08/06 01:30:33]

Totally thought about that!

But... enabling callbacks is not a synchronous operation. So doing it later
could affect when the first memory allocation callback happens, which could
intern affect when first raster starts, which can affect timings of a lot of
things.

So decided to not do that :)

[boliu, 2015/08/06 01:41:37]

And then I realize these two things actually happen at the exact same time. So
overriding this it is!

+        base::Bind(&ContextProviderCommandBuffer::OnMemoryAllocationChanged,
+                   base::Unretained(this)));
+  }
   return true;
 }