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 CreateBackgroundHostForExtensionLoad(
     ExtensionProcessManager* manager, const Extension* extension) {
-  // Start the process for the master page, if it exists.
+  // Start the process for the master page, if it exists and we're not lazy.
   if (extension->background_url().is_valid())
     manager->CreateBackgroundHost(extension, extension->background_url());
 }
 
-static void CreateBackgroundHosts(
+static void CreateBackgroundHostsForProfileStartup(
     ExtensionProcessManager* manager, const ExtensionList* extensions) {
   for (ExtensionList::const_iterator extension = extensions->begin();
        extension != extensions->end(); ++extension) {
-    CreateBackgroundHost(manager, *extension);
+    CreateBackgroundHostForExtensionLoad(manager, *extension);
   }
 }
 
 }  // namespace
 
 extern bool g_log_bug53991;
 
 //
 // ExtensionProcessManager
 //
@@ skipping 201 matching lines @@
 
 bool ExtensionProcessManager::HasExtensionHost(ExtensionHost* host) const {
   return all_hosts_.find(host) != all_hosts_.end();
 }
 
 void ExtensionProcessManager::Observe(int type,
                                       const NotificationSource& source,
                                       const NotificationDetails& details) {
   switch (type) {
     case chrome::NOTIFICATION_EXTENSIONS_READY: {
-      CreateBackgroundHosts(this,
+      if (CommandLine::ForCurrentProcess()->HasSwitch(

[Aaron Boodman, 2011/08/23 22:41:16]

As discussed in chat, try moving these to
CreateBackgroundHostsForExtensionLoad().

[Tessa MacDuff, 2011/08/24 00:34:23]

Done.

+              switches::kEnableLazyBackgroundPages))
+        break;
+      CreateBackgroundHostsForProfileStartup(this,
           Source<Profile>(source).ptr()->GetExtensionService()->extensions());
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_LOADED: {
+      if (CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kEnableLazyBackgroundPages))
+        break;
       ExtensionService* service =
           Source<Profile>(source).ptr()->GetExtensionService();
       if (service->is_ready()) {
         const Extension* extension = Details<const Extension>(details).ptr();
-        ::CreateBackgroundHost(this, extension);
+        ::CreateBackgroundHostForExtensionLoad(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 151 matching lines @@
   ExtensionService* service = profile->GetExtensionService();
   return service && service->IsIncognitoEnabled(extension->id());
 }
 
 void IncognitoExtensionProcessManager::Observe(
     int type,
     const NotificationSource& source,
     const NotificationDetails& details) {
   switch (type) {
     case chrome::NOTIFICATION_BROWSER_WINDOW_READY: {
+      if (CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kEnableLazyBackgroundPages))
+        break;
       // We want to spawn our background hosts as soon as the user opens an
       // incognito window. Watch for new browsers and create the hosts if
       // it matches our profile.
       Browser* browser = Source<Browser>(source).ptr();
       if (browser->profile() == browsing_instance_->browser_context()) {
         // On Chrome OS, a login screen is implemented as a browser.
         // This browser has no extension service.  In this case,
         // service will be NULL.
         Profile* profile =
             Profile::FromBrowserContext(browsing_instance_->browser_context());
         ExtensionService* service = profile->GetExtensionService();
         if (service && service->is_ready())
-          CreateBackgroundHosts(this, service->extensions());
+          CreateBackgroundHostsForProfileStartup(this, service->extensions());
       }
       break;
     }
     default:
       ExtensionProcessManager::Observe(type, source, details);
       break;
   }
 }