Let DelegateFrameHost in Mac and Android use correct FrameSinkId during creation

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 8a0995a4c78a0a1f31be7143b6b29fa65c6355cd..0fdb76366bacc0473858a711149e2c3d0c75731a 100644
--- a/content/browser/compositor/gpu_process_transport_factory.cc
+++ b/content/browser/compositor/gpu_process_transport_factory.cc
@@ -690,6 +690,11 @@ 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_++);
 }