Centralize FrameSinkId allocation in one place

android_webview/browser/surfaces_instance.cc

Index: android_webview/browser/surfaces_instance.cc
diff --git a/android_webview/browser/surfaces_instance.cc b/android_webview/browser/surfaces_instance.cc
index 93f515526b549b23af5cf567b1e46958b37e3692..cbd754139a098f6a5d30da833877f03d881268ae 100644
--- a/android_webview/browser/surfaces_instance.cc
+++ b/android_webview/browser/surfaces_instance.cc
@@ -38,8 +38,7 @@ scoped_refptr<SurfacesInstance> SurfacesInstance::GetOrCreateInstance() {
   return make_scoped_refptr(new SurfacesInstance);
 }
 
-SurfacesInstance::SurfacesInstance()
-    : next_client_id_(1u), frame_sink_id_(AllocateFrameSinkId()) {
+SurfacesInstance::SurfacesInstance() : frame_sink_id_(AllocateFrameSinkId()) {
   cc::RendererSettings settings;
 
   // Should be kept in sync with compositor_impl_android.cc.
@@ -89,7 +88,7 @@ void SurfacesInstance::DisplayOutputSurfaceLost() {
 }
 
 cc::FrameSinkId SurfacesInstance::AllocateFrameSinkId() {
-  return cc::FrameSinkId(next_client_id_++, 0 /* sink_id */);
+  return frame_sink_id_allocator_.NextFrameSinkId();
 }
 
 cc::SurfaceManager* SurfacesInstance::GetSurfaceManager() {