Centralize FrameSinkId allocation in one place

content/browser/compositor/gpu_process_transport_factory.cc

Index: content/browser/compositor/gpu_process_transport_factory.cc
diff --git a/content/browser/compositor/gpu_process_transport_factory.cc b/content/browser/compositor/gpu_process_transport_factory.cc
index 713812a1012a9e7a75bde89fbb3c362a4d9426a0..c9023603115834b013cd5d95417162f244a19653 100644
--- a/content/browser/compositor/gpu_process_transport_factory.cc
+++ b/content/browser/compositor/gpu_process_transport_factory.cc
@@ -175,7 +175,10 @@ struct GpuProcessTransportFactory::PerCompositorData {
 };
 
 GpuProcessTransportFactory::GpuProcessTransportFactory()
-    : task_graph_runner_(new cc::SingleThreadTaskGraphRunner),
+    : frame_sink_id_allocator_(
+          0 /* client_id, not to conflict with the client_id

[boliu, 2017/02/15 23:58:56]

nit: 0u everwhere

[Fady Samuel, 2017/02/17 14:00:24]

nit: Maybe add a constexpr at the top of the file instead and put the comment
there. This comment looks a bit awkward inline here.

[xlai (Olivia), 2017/02/17 15:55:11]

Done.

[xlai (Olivia), 2017/02/17 15:55:11]

Done.

+                                   generated from RenderWidgetHostImpl */),
+      task_graph_runner_(new cc::SingleThreadTaskGraphRunner),
       callback_factory_(this) {
   cc::SetClientNameForMetrics("Browser");
 
@@ -689,12 +692,7 @@ GpuProcessTransportFactory::GetContextFactoryPrivate() {
 }
 
 cc::FrameSinkId GpuProcessTransportFactory::AllocateFrameSinkId() {
-  // The FrameSinkId generated here must be unique with
-  // RenderWidgetHostViewAura's
-  // and RenderWidgetHostViewMac's FrameSinkId allocation.
-  // TODO(crbug.com/685777): Centralize allocation in one place for easier
-  // maintenance.
-  return cc::FrameSinkId(0, next_sink_id_++);
+  return frame_sink_id_allocator_.NextFrameSinkId();
 }
 
 void GpuProcessTransportFactory::SetDisplayVisible(ui::Compositor* compositor,