ApplicationManager: Use callback to get notified on application shutdown.

shell/context.h

Index: shell/context.h
diff --git a/shell/context.h b/shell/context.h
index 645764d4c2c542ff94c96b1eb5603556f983d44f..b266b1d5a20a60366d78e58597db0f3ad701fe5d 100644
--- a/shell/context.h
+++ b/shell/context.h
@@ -67,13 +67,14 @@ class Context : public ApplicationManager::Delegate,
   class NativeViewportApplicationLoader;
 
   // ApplicationManager::Delegate overrides.
-  void OnApplicationError(const GURL& url) override;
   GURL ResolveURL(const GURL& url) override;
   GURL ResolveMappings(const GURL& url) override;
 
   // ProcessDelegate implementation.
   void OnShutdownComplete() override;
 
+  void OnApplicationEnd(const GURL& url);
+
   std::set<GURL> app_urls_;
   scoped_ptr<TaskRunners> task_runners_;
   scoped_ptr<ExternalApplicationListener> listener_;