Lazy creating of background pages --enable-lazy-background-pages)

chrome/browser/extensions/extension_process_manager.cc

 // Copyright (c) 2011 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/command_line.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
 
 #include "chrome/browser/ui/browser_window.h"
 #include "content/browser/browsing_instance.h"
 #if defined(OS_MACOSX)
 #include "chrome/browser/extensions/extension_host_mac.h"
 #endif
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/common/chrome_notification_types.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/url_constants.h"
 #include "content/browser/site_instance.h"
 #include "content/browser/tab_contents/tab_contents.h"
 #include "content/common/notification_service.h"
 
 namespace {
 
 // Incognito profiles use this process manager. It is mostly a shim that decides
 // whether to fall back on the original profile's ExtensionProcessManager based
@@ skipping 21 matching lines @@
   // Returns the extension for an URL, which can either be a chrome-extension
   // URL or a web app URL.
   const Extension* GetExtensionOrAppByURL(const GURL& url);
 
   // Returns true if the extension is allowed to run in incognito mode.
   bool IsIncognitoEnabled(const Extension* extension);
 
   ExtensionProcessManager* original_manager_;
 };
 
-static void CreateBackgroundHost(
+static void MaybeCreateBackgroundHost(

[Aaron Boodman, 2011/08/18 19:25:55]

Sorry to nitpick the but "Maybe" functions always bug me. Maybe based on what?
The name doesn't describe what the function does very well.

How about names like:

CreateBackgroundHosts -> CreateBackgroundHostsForProfileStartup
CreateBackgroundHost -> CreateBackgroundHostForExtensionLoad

I realize they are a bit long, but at least they try to describe the behavior.
And then you could just have a separate CreateBackgroundHost that does it
unconditionally.

[Tessa MacDuff, 2011/08/23 18:18:42]

Done.  I also moved the switch check up out of these functions to Observe(). 
Let me know what you think.

     ExtensionProcessManager* manager, const Extension* extension) {
-  // Start the process for the master page, if it exists.
-  if (extension->background_url().is_valid())
+  // Start the process for the master page, if it exists and we're not lazy.
+  if (extension->background_url().is_valid() &&
+      !CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableLazyBackgroundPages))
     manager->CreateBackgroundHost(extension, extension->background_url());
 }
 
 static void CreateBackgroundHosts(
     ExtensionProcessManager* manager, const ExtensionList* extensions) {
   for (ExtensionList::const_iterator extension = extensions->begin();
        extension != extensions->end(); ++extension) {
-    CreateBackgroundHost(manager, *extension);
+    MaybeCreateBackgroundHost(manager, *extension);
   }
 }
 
 }  // namespace
 
 extern bool g_log_bug53991;
 
 //
 // ExtensionProcessManager
 //
@@ skipping 211 matching lines @@
       CreateBackgroundHosts(this,
           Source<Profile>(source).ptr()->GetExtensionService()->extensions());
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_LOADED: {
       ExtensionService* service =
           Source<Profile>(source).ptr()->GetExtensionService();
       if (service->is_ready()) {
         const Extension* extension = Details<const Extension>(details).ptr();
-        ::CreateBackgroundHost(this, extension);
+        ::MaybeCreateBackgroundHost(this, extension);
       }
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_UNLOADED: {
       const Extension* extension =
           Details<UnloadedExtensionInfo>(details)->extension;
       for (ExtensionHostSet::iterator iter = background_hosts_.begin();
            iter != background_hosts_.end(); ++iter) {
         ExtensionHost* host = *iter;
@@ skipping 172 matching lines @@
         if (service && service->is_ready())
           CreateBackgroundHosts(this, service->extensions());
       }
       break;
     }
     default:
       ExtensionProcessManager::Observe(type, source, details);
       break;
   }
 }