Move handling of DraggableRegionsChanged notification from "view" to "frame".

extensions/browser/app_window/app_window_contents.h

Index: extensions/browser/app_window/app_window_contents.h
diff --git a/extensions/browser/app_window/app_window_contents.h b/extensions/browser/app_window/app_window_contents.h
index 4afa13d1ed16eb9c744a6d398784fd7b12658166..6446f45af499b6cd40dea5fab33a9d980f8847ad 100644
--- a/extensions/browser/app_window/app_window_contents.h
+++ b/extensions/browser/app_window/app_window_contents.h
@@ -45,10 +45,12 @@ class AppWindowContentsImpl : public AppWindowContents,
 
  private:
   // content::WebContentsObserver
-  bool OnMessageReceived(const IPC::Message& message) override;
+  bool OnMessageReceived(const IPC::Message& message,
+                         content::RenderFrameHost* sender) override;
   void ReadyToCommitNavigation(content::NavigationHandle* handle) override;
 
-  void UpdateDraggableRegions(const std::vector<DraggableRegion>& regions);
+  void UpdateDraggableRegions(content::RenderFrameHost* sender,
+                              const std::vector<DraggableRegion>& regions);
   void SuspendRenderFrameHost(content::RenderFrameHost* rfh);
 
   AppWindow* host_;  // This class is owned by |host_|