Keep lazy background page alive while there are pending network requests or

chrome/browser/renderer_host/chrome_render_view_host_observer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/renderer_host/chrome_render_view_host_observer.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/net/predictor.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 16 matching lines @@
     : content::RenderViewHostObserver(render_view_host),
       predictor_(predictor) {
   SiteInstance* site_instance = render_view_host->site_instance();
   profile_ = Profile::FromBrowserContext(
       site_instance->GetBrowserContext());
 
   InitRenderViewHostForExtensions();
 }
 
 ChromeRenderViewHostObserver::~ChromeRenderViewHostObserver() {
-  RemoveRenderViewHostForExtensions(render_view_host());
+  if (render_view_host())
+    RemoveRenderViewHostForExtensions(render_view_host());
 }
 
 void ChromeRenderViewHostObserver::RenderViewHostInitialized() {
   InitRenderViewForExtensions();
 }
 
 void ChromeRenderViewHostObserver::RenderViewHostDestroyed(
     RenderViewHost* rvh) {
   RemoveRenderViewHostForExtensions(rvh);
   delete this;
@@ skipping 113 matching lines @@
   if (process_manager)
     process_manager->UnregisterRenderViewHost(rvh);
 }
 
 void ChromeRenderViewHostObserver::OnFocusedEditableNodeTouched() {
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_FOCUSED_EDITABLE_NODE_TOUCHED,
       content::Source<RenderViewHost>(render_view_host()),
       content::NotificationService::NoDetails());
 }