Enable sync allocation of GpuMemoryBuffers from the browser process.

content/browser/gpu/browser_gpu_channel_host_factory.cc

Index: content/browser/gpu/browser_gpu_channel_host_factory.cc
diff --git a/content/browser/gpu/browser_gpu_channel_host_factory.cc b/content/browser/gpu/browser_gpu_channel_host_factory.cc
index b35d64f3255ec73f58561e98a56edc4976159879..560ec7afff7552ec9c7a28ae6db3ab14441d6948 100644
--- a/content/browser/gpu/browser_gpu_channel_host_factory.cc
+++ b/content/browser/gpu/browser_gpu_channel_host_factory.cc
@@ -492,11 +492,12 @@ void BrowserGpuChannelHostFactory::AllocateGpuMemoryBufferOnIO(
     return;
   }
 
-  request->result = GpuMemoryBufferImpl::Create(
-                        gfx::Size(request->width, request->height),
-                        request->internalformat,
-                        request->usage).PassAs<gfx::GpuMemoryBuffer>();
-  request->event.Signal();
+  GpuMemoryBufferImpl::Create(
+      gfx::Size(request->width, request->height),
+      request->internalformat,
+      request->usage,
+      base::Bind(&BrowserGpuChannelHostFactory::GpuMemoryBufferImplCreatedOnIO,
+                 base::Unretained(request)));
 }
 
 // static
@@ -504,6 +505,15 @@ void BrowserGpuChannelHostFactory::DeleteGpuMemoryBufferOnIO(
     scoped_ptr<gfx::GpuMemoryBuffer> buffer) {
 }
 
+// static
+void BrowserGpuChannelHostFactory::GpuMemoryBufferImplCreatedOnIO(

[reveman, 2014/09/09 17:18:26]

I think this should be named "OnGpuMemoryBufferCreated" or
"OnGpuMemoryBufferAllocated". There's obviously a conflict if using "Created"
which I think we need to address no matter what. It's getting pretty confusing
to have this class implement both the GpuMemoryBuffer part of
GpuChannelHostFactory and GpuMemoryBufferFactoryHost. How about we move the
GpuMemoryBufferFactoryHost part out into a GpuMemoryBufferFactoryHostImpl class?

[alexst (slow to review), 2014/09/09 21:53:57]

Yeah, the namespace is getting crowded, I'll add GpuMemoryBufferFactoryHostImpl.

+    AllocateGpuMemoryBufferRequest* request,
+    scoped_ptr<GpuMemoryBufferImpl> buffer) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

[reveman, 2014/09/09 17:18:26]

nit: blank line after this DCHECK to be consistent in style with other
GpuMemoryBuffer related functions.

[alexst (slow to review), 2014/09/09 21:53:56]

Done.

+  request->result = buffer.PassAs<gfx::GpuMemoryBuffer>();
+  request->event.Signal();
+}
+
 void BrowserGpuChannelHostFactory::OnGpuMemoryBufferCreated(
     uint32 request_id,
     const gfx::GpuMemoryBufferHandle& handle) {