Implement the ability to layout test Web Worker-based Notifications.

content/shell/browser/layout_test/layout_test_content_browser_client.h

Index: content/shell/browser/layout_test/layout_test_content_browser_client.h
diff --git a/content/shell/browser/layout_test/layout_test_content_browser_client.h b/content/shell/browser/layout_test/layout_test_content_browser_client.h
index f58032a0e4142900a26d3ac1b8015e3c3f594f0a..3049c06a9717fbac0fc631453720f9161972e7e6 100644
--- a/content/shell/browser/layout_test/layout_test_content_browser_client.h
+++ b/content/shell/browser/layout_test/layout_test_content_browser_client.h
@@ -33,6 +33,11 @@ class LayoutTestContentBrowserClient : public ShellContentBrowserClient {
       const GURL& source_url,
       ResourceContext* context,
       int render_process_id) override;
+  void ShowDesktopNotification(
+      const ShowDesktopNotificationHostMsgParams& params,
+      RenderFrameHost* render_frame_host,
+      scoped_ptr<DesktopNotificationDelegate> delegate,
+      base::Closure* cancel_callback) override;
 
  private:
   scoped_ptr<LayoutTestNotificationManager> layout_test_notification_manager_;