Fix a bug where we'd leak ResourceMessageFilters and BrowserRenderProcessHosts

chrome/browser/extensions/extension_process_manager.h

Index: chrome/browser/extensions/extension_process_manager.h
diff --git a/chrome/browser/extensions/extension_process_manager.h b/chrome/browser/extensions/extension_process_manager.h
index e154a331314bffa798dbed729cec039698e9aa3f..d2d62effa59769be9e86ae05ab3104d21ee07873 100644
--- a/chrome/browser/extensions/extension_process_manager.h
+++ b/chrome/browser/extensions/extension_process_manager.h
@@ -83,6 +83,9 @@ class ExtensionProcessManager : public NotificationObserver {
   // Called just after |host| is created so it can be registered in our lists.
   void OnExtensionHostCreated(ExtensionHost* host, bool is_background);
 
+  // Called on browser shutdown to close our extension hosts.
+  void CloseBackgroundHosts();
+
   NotificationRegistrar registrar_;
 
   // The set of all ExtensionHosts managed by this process manager.