Rewire Android WebView's compositor changed signal.

content/browser/android/synchronous_compositor_host.h

Index: content/browser/android/synchronous_compositor_host.h
diff --git a/content/browser/android/synchronous_compositor_host.h b/content/browser/android/synchronous_compositor_host.h
index 39f496f20c062cdaa4c01a6ef5a05daaf5033c9b..b3c9a9d5e55e96ddce4f6f0dc40215ee076cc277 100644
--- a/content/browser/android/synchronous_compositor_host.h
+++ b/content/browser/android/synchronous_compositor_host.h
@@ -68,7 +68,6 @@ class SynchronousCompositorHost : public SynchronousCompositor {
   void DidOverscroll(const DidOverscrollParams& over_scroll_params);
   void DidSendBeginFrame();
   bool OnMessageReceived(const IPC::Message& message);
-  void DidBecomeCurrent();
 
  private:
   class ScopedSendZeroMemory;
@@ -89,6 +88,7 @@ class SynchronousCompositorHost : public SynchronousCompositor {
   RenderWidgetHostViewAndroid* const rwhva_;
   SynchronousCompositorClient* const client_;
   const scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
+  const int process_id_;
   const int routing_id_;
   IPC::Sender* const sender_;
   const bool use_in_process_zero_copy_software_draw_;