Centralize FrameSinkId allocation in one place

android_webview/browser/surfaces_instance.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ANDROID_WEBVIEW_BROWSER_SURFACES_INSTANCE_H_
 #define ANDROID_WEBVIEW_BROWSER_SURFACES_INSTANCE_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "cc/surfaces/compositor_frame_sink_support_client.h"
 #include "cc/surfaces/display_client.h"
 #include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/frame_sink_id_allocator.h"
 #include "cc/surfaces/surface_id.h"
 
 namespace cc {
 class BeginFrameSource;
 class CompositorFrameSinkSupport;
 class Display;
 class SurfaceIdAllocator;
 class SurfaceManager;
 }
 
@@ skipping 39 matching lines @@
   void DisplayDidDrawAndSwap() override {}
 
   // cc::CompositorFrameSinkSupportClient implementation.
   void DidReceiveCompositorFrameAck() override;
   void OnBeginFrame(const cc::BeginFrameArgs& args) override;
   void WillDrawSurface() override;
   void ReclaimResources(const cc::ReturnedResourceArray& resources) override;
 
   void SetEmptyRootFrame();
 
-  uint32_t next_client_id_;
+  cc::FrameSinkIdAllocator frame_sink_id_allocator_;
 
   cc::FrameSinkId frame_sink_id_;
 
   std::unique_ptr<cc::SurfaceManager> surface_manager_;
   std::unique_ptr<cc::BeginFrameSource> begin_frame_source_;
   std::unique_ptr<cc::Display> display_;
   std::unique_ptr<cc::SurfaceIdAllocator> surface_id_allocator_;
   std::unique_ptr<cc::CompositorFrameSinkSupport> support_;
 
   cc::LocalSurfaceId root_id_;
   std::vector<cc::SurfaceId> child_ids_;
 
   // This is owned by |display_|.
   ParentOutputSurface* output_surface_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfacesInstance);
 };
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_SURFACES_INSTANCE_H_