Introduce background.scripts feature for extension manifests.

chrome/browser/extensions/extension_process_manager.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 "base/bind.h"
 #include "base/command_line.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
 
 #include "chrome/browser/ui/browser_window.h"
 #include "content/browser/browsing_instance.h"
@@ skipping 51 matching lines @@
   bool IsIncognitoEnabled(const Extension* extension);
 
   ExtensionProcessManager* original_manager_;
 };
 
 static void CreateBackgroundHostForExtensionLoad(
     ExtensionProcessManager* manager, const Extension* extension) {
   // Start the process for the master page, if it exists and we're not lazy.
   if (!CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableLazyBackgroundPages) &&
-      extension->background_url().is_valid())
-    manager->CreateBackgroundHost(extension, extension->background_url());
+      extension->has_background_page()) {
+    manager->CreateBackgroundHost(extension, extension->GetBackgroundURL());
+  }
 }
 
 static void CreateBackgroundHostsForProfileStartup(
     ExtensionProcessManager* manager, const ExtensionSet* extensions) {
   for (ExtensionSet::const_iterator extension = extensions->begin();
        extension != extensions->end(); ++extension) {
     CreateBackgroundHostForExtensionLoad(manager, *extension);
   }
 }
 
@@ skipping 414 matching lines @@
         if (service && service->is_ready())
           CreateBackgroundHostsForProfileStartup(this, service->extensions());
       }
       break;
     }
     default:
       ExtensionProcessManager::Observe(type, source, details);
       break;
   }
 }