webview: Initialize synchronous compositor after first activation.

content/browser/android/in_process/synchronous_compositor_impl.h

 // Copyright 2013 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 CONTENT_BROWSER_ANDROID_IN_PROCESS_SYNCHRONOUS_COMPOSITOR_IMPL_H_
 #define CONTENT_BROWSER_ANDROID_IN_PROCESS_SYNCHRONOUS_COMPOSITOR_IMPL_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 81 matching lines @@
   void DidOverscroll(const DidOverscrollParams& params);
   void DidStopFlinging();
 
  private:
   friend class WebContentsUserData<SynchronousCompositorImpl>;
   friend class SynchronousCompositor;
   explicit SynchronousCompositorImpl(WebContents* contents);
   ~SynchronousCompositorImpl() override;
 
   void SetClient(SynchronousCompositorClient* compositor_client);
+  void RegisterWithClient();
   void UpdateFrameMetaData(const cc::CompositorFrameMetadata& frame_info);
   void DidActivatePendingTree();
   void DeliverMessages();
   bool CalledOnValidThread() const;
   void UpdateNeedsBeginFrames();
   void SetInputHandler(cc::InputHandler* input_handler);
 
   SynchronousCompositorClient* compositor_client_;
   SynchronousCompositorOutputSurface* output_surface_;
   SynchronousCompositorExternalBeginFrameSource* begin_frame_source_;
   WebContents* contents_;
   const int routing_id_;
   cc::InputHandler* input_handler_;
+  bool registered_with_client_;
   bool is_active_;
   bool renderer_needs_begin_frames_;
 
   base::WeakPtrFactory<SynchronousCompositorImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SynchronousCompositorImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_IN_PROCESS_SYNCHRONOUS_COMPOSITOR_IMPL_H_