Reduce SurfaceIdAllocator usage and tie SurfaceFactory to a single FrameSinkId

android_webview/browser/surfaces_instance.h

Index: android_webview/browser/surfaces_instance.h
diff --git a/android_webview/browser/surfaces_instance.h b/android_webview/browser/surfaces_instance.h
index 53a7ddc659f3e7805c05ff553bc189d2d780cdd0..c3a4093555478448c9c68ee6890bb7c7e97c0db4 100644
--- a/android_webview/browser/surfaces_instance.h
+++ b/android_webview/browser/surfaces_instance.h
@@ -10,6 +10,7 @@
 
 #include "base/memory/ref_counted.h"
 #include "cc/surfaces/display_client.h"
+#include "cc/surfaces/frame_sink_id.h"
 #include "cc/surfaces/surface_factory_client.h"
 #include "cc/surfaces/surface_id.h"
 
@@ -69,7 +70,9 @@ class SurfacesInstance : public base::RefCounted<SurfacesInstance>,
 
   void SetEmptyRootFrame();
 
-  uint32_t next_frame_sink_id_;
+  uint32_t next_client_id_;
+
+  cc::FrameSinkId frame_sink_id_;
 
   std::unique_ptr<cc::SurfaceManager> surface_manager_;
   std::unique_ptr<cc::Display> display_;