Revert 283678 "Refactor code that defers extension background pa..."

This broke Chrome OS valgrind bots, for example:
http://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%284%29/builds/27033

> Refactor code that defers extension background page loading
> 
> src/extensions depends on chrome::NOTIFICATION_PROFILE_CREATED to support deferred loading of extension background pages when the profile isn't ready yet. This is a layering violation.
> 
> * Remove Chrome concepts like "browser window ready" and "profile created" from ProcessManager. Introduce ProcessManagerDelegate with a general concept of deferring background page loading.
> * Consolidate all the tricky Chrome-specific background page loading rules into ChromeProcessManagerDelegate. This keeps all the rules in one place. Annotate each block of special case code with the bug that inspired it.
> * Extend unit test coverage for ProcessManager.
> 
> This will make it easier to eliminate chrome::NOTIFICATION_PROFILE_DESTROYED in ProcessManager in a later CL.
> 
> BUG=392658
> TEST=unit_tests ProcessManagerTest, browser_tests ProcessManagerBrowserTest, manual
> 
> Review URL: https://codereview.chromium.org/381283002

TBR=jamescook@chromium.org

Review URL: https://codereview.chromium.org/399153002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283801 0039d316-1c4b-4281-b951-d872f2087c98

18 files changed, 174 insertions, 443 deletions

diff --git a/apps/shell/browser/shell_extensions_browser_client.cc b/apps/shell/browser/shell_extensions_browser_client.cc
index 54b0df8..76f4a83 100644
--- a/apps/shell/browser/shell_extensions_browser_client.cc
+++ b/apps/shell/browser/shell_extensions_browser_client.cc
@@ -183,9 +183,14 @@ void ShellExtensionsBrowserClient::GetEarlyExtensionPrefsObservers(
     content::BrowserContext* context,
     std::vector<ExtensionPrefsObserver*>* observers) const {}
 
-ProcessManagerDelegate*
-ShellExtensionsBrowserClient::GetProcessManagerDelegate() const {
-  return NULL;
+bool ShellExtensionsBrowserClient::DeferLoadingBackgroundHosts(
+    BrowserContext* context) const {
+  return false;
+}
+
+bool ShellExtensionsBrowserClient::IsBackgroundPageAllowed(
+    BrowserContext* context) const {
+  return true;
 }
 
 scoped_ptr<ExtensionHostDelegate>
diff --git a/apps/shell/browser/shell_extensions_browser_client.h b/apps/shell/browser/shell_extensions_browser_client.h
index b6a20f7..2013c6d 100644
--- a/apps/shell/browser/shell_extensions_browser_client.h
+++ b/apps/shell/browser/shell_extensions_browser_client.h
@@ -59,7 +59,10 @@ class ShellExtensionsBrowserClient : public ExtensionsBrowserClient {
   virtual void GetEarlyExtensionPrefsObservers(
       content::BrowserContext* context,
       std::vector<ExtensionPrefsObserver*>* observers) const OVERRIDE;
-  virtual ProcessManagerDelegate* GetProcessManagerDelegate() const OVERRIDE;
+  virtual bool DeferLoadingBackgroundHosts(content::BrowserContext* context)
+      const OVERRIDE;
+  virtual bool IsBackgroundPageAllowed(content::BrowserContext* context)
+      const OVERRIDE;
   virtual scoped_ptr<ExtensionHostDelegate> CreateExtensionHostDelegate()
       OVERRIDE;
   virtual bool DidVersionUpdate(content::BrowserContext* context) OVERRIDE;
diff --git a/chrome/browser/extensions/chrome_extensions_browser_client.cc b/chrome/browser/extensions/chrome_extensions_browser_client.cc
index db2ae3b..c66d023 100644
--- a/chrome/browser/extensions/chrome_extensions_browser_client.cc
+++ b/chrome/browser/extensions/chrome_extensions_browser_client.cc
@@ -21,6 +21,7 @@
 #include "chrome/browser/external_protocol/external_protocol_handler.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/ui/browser_finder.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
@@ -41,14 +42,12 @@
 #include "chrome/browser/extensions/activity_log/activity_log.h"
 #include "chrome/browser/extensions/api/chrome_extensions_api_client.h"
 #include "chrome/browser/extensions/api/content_settings/content_settings_service.h"
-#include "chrome/browser/extensions/chrome_process_manager_delegate.h"
 #endif
 
 namespace extensions {
 
 ChromeExtensionsBrowserClient::ChromeExtensionsBrowserClient() {
 #if defined(ENABLE_EXTENSIONS)
-  process_manager_delegate_.reset(new ChromeProcessManagerDelegate);
   api_client_.reset(new ChromeExtensionsAPIClient);
 #endif
   // Only set if it hasn't already been set (e.g. by a test).
@@ -159,15 +158,35 @@ void ChromeExtensionsBrowserClient::GetEarlyExtensionPrefsObservers(
 #endif
 }
 
-ProcessManagerDelegate*
-ChromeExtensionsBrowserClient::GetProcessManagerDelegate() const {
-#if defined(ENABLE_EXTENSIONS)
-  return process_manager_delegate_.get();
+bool ChromeExtensionsBrowserClient::DeferLoadingBackgroundHosts(
+    content::BrowserContext* context) const {
+  Profile* profile = static_cast<Profile*>(context);
+
+  // The profile may not be valid yet if it is still being initialized.
+  // In that case, defer loading, since it depends on an initialized profile.
+  // http://crbug.com/222473
+  if (!g_browser_process->profile_manager()->IsValidProfile(profile))
+    return true;
+
+#if defined(OS_ANDROID)
+  return false;
 #else
-  return NULL;
+  // There are no browser windows open and the browser process was
+  // started to show the app launcher.
+  return chrome::GetTotalBrowserCountForProfile(profile) == 0 &&
+         CommandLine::ForCurrentProcess()->HasSwitch(switches::kShowAppList);
 #endif
 }
 
+bool ChromeExtensionsBrowserClient::IsBackgroundPageAllowed(
+    content::BrowserContext* context) const {
+  // Returns true if current session is Guest mode session and current
+  // browser context is *not* off-the-record. Such context is artificial and
+  // background page shouldn't be created in it.
+  return !static_cast<Profile*>(context)->IsGuestSession() ||
+         context->IsOffTheRecord();
+}
+
 scoped_ptr<ExtensionHostDelegate>
 ChromeExtensionsBrowserClient::CreateExtensionHostDelegate() {
   return scoped_ptr<ExtensionHostDelegate>(new ChromeExtensionHostDelegate);
diff --git a/chrome/browser/extensions/chrome_extensions_browser_client.h b/chrome/browser/extensions/chrome_extensions_browser_client.h
index 5957838..3c4a2c6 100644
--- a/chrome/browser/extensions/chrome_extensions_browser_client.h
+++ b/chrome/browser/extensions/chrome_extensions_browser_client.h
@@ -26,7 +26,6 @@ namespace extensions {
 
 class ChromeComponentExtensionResourceManager;
 class ChromeExtensionsAPIClient;
-class ChromeProcessManagerDelegate;
 class ContentSettingsPrefsObserver;
 
 // Implementation of extensions::BrowserClient for Chrome, which includes
@@ -77,7 +76,10 @@ class ChromeExtensionsBrowserClient : public ExtensionsBrowserClient {
   virtual void GetEarlyExtensionPrefsObservers(
       content::BrowserContext* context,
       std::vector<ExtensionPrefsObserver*>* observers) const OVERRIDE;
-  virtual ProcessManagerDelegate* GetProcessManagerDelegate() const OVERRIDE;
+  virtual bool DeferLoadingBackgroundHosts(
+      content::BrowserContext* context) const OVERRIDE;
+  virtual bool IsBackgroundPageAllowed(
+      content::BrowserContext* context) const OVERRIDE;
   virtual scoped_ptr<ExtensionHostDelegate> CreateExtensionHostDelegate()
       OVERRIDE;
   virtual bool DidVersionUpdate(content::BrowserContext* context) OVERRIDE;
@@ -100,9 +102,6 @@ class ChromeExtensionsBrowserClient : public ExtensionsBrowserClient {
   ChromeNotificationObserver notification_observer_;
 
 #if defined(ENABLE_EXTENSIONS)
-  // Support for ProcessManager.
-  scoped_ptr<ChromeProcessManagerDelegate> process_manager_delegate_;
-
   // Client for API implementations.
   scoped_ptr<ChromeExtensionsAPIClient> api_client_;
 #endif
diff --git a/chrome/browser/extensions/chrome_notification_observer.cc b/chrome/browser/extensions/chrome_notification_observer.cc
index c8e6016..5d966c8 100644
--- a/chrome/browser/extensions/chrome_notification_observer.cc
+++ b/chrome/browser/extensions/chrome_notification_observer.cc
@@ -4,22 +4,59 @@
 
 #include "chrome/browser/extensions/chrome_notification_observer.h"
 
+#include "base/logging.h"
+#include "chrome/browser/chrome_notification_types.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/browser.h"
 #include "chrome/common/extensions/features/feature_channel.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_process_host.h"
+#include "extensions/browser/extension_system.h"
+#include "extensions/browser/process_manager.h"
 #include "extensions/common/extension_messages.h"
 
 namespace extensions {
 
 ChromeNotificationObserver::ChromeNotificationObserver() {
   registrar_.Add(this,
+                 chrome::NOTIFICATION_BROWSER_WINDOW_READY,
+                 content::NotificationService::AllSources());
+  registrar_.Add(this,
                  content::NOTIFICATION_RENDERER_PROCESS_CREATED,
                  content::NotificationService::AllBrowserContextsAndSources());
 }
 
 ChromeNotificationObserver::~ChromeNotificationObserver() {}
 
+void ChromeNotificationObserver::OnBrowserWindowReady(Browser* browser) {
+  Profile* profile = browser->profile();
+  DCHECK(profile);
+
+  // Inform the process manager for this profile that the window is ready.
+  // We continue to observe the notification in case browser windows open for
+  // a related incognito profile or other regular profiles.
+  extensions::ProcessManager* manager =
+      ExtensionSystem::Get(profile)->process_manager();
+  if (!manager)  // Tests may not have a process manager.
+    return;
+  DCHECK_EQ(profile, manager->GetBrowserContext());
+  manager->OnBrowserWindowReady();
+
+  // For incognito profiles also inform the original profile's process manager
+  // that the window is ready. This will usually be a no-op because the
+  // original profile's process manager should have been informed when the
+  // non-incognito window opened.
+  if (profile->IsOffTheRecord()) {
+    Profile* original_profile = profile->GetOriginalProfile();
+    extensions::ProcessManager* original_manager =
+        ExtensionSystem::Get(original_profile)->process_manager();
+    DCHECK(original_manager);
+    DCHECK_EQ(original_profile, original_manager->GetBrowserContext());
+    original_manager->OnBrowserWindowReady();
+  }
+}
+
 void ChromeNotificationObserver::OnRendererProcessCreated(
     content::RenderProcessHost* process) {
   // Extensions need to know the channel for API restrictions. Send the channel
@@ -31,6 +68,12 @@ void ChromeNotificationObserver::Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) {
   switch (type) {
+    case chrome::NOTIFICATION_BROWSER_WINDOW_READY: {
+      Browser* browser = content::Source<Browser>(source).ptr();
+      OnBrowserWindowReady(browser);
+      break;
+    }
+
     case content::NOTIFICATION_RENDERER_PROCESS_CREATED: {
       content::RenderProcessHost* process =
           content::Source<content::RenderProcessHost>(source).ptr();
diff --git a/chrome/browser/extensions/chrome_notification_observer.h b/chrome/browser/extensions/chrome_notification_observer.h
index 8045b15..a31dc87 100644
--- a/chrome/browser/extensions/chrome_notification_observer.h
+++ b/chrome/browser/extensions/chrome_notification_observer.h
@@ -25,7 +25,8 @@ class ChromeNotificationObserver : public content::NotificationObserver {
   ChromeNotificationObserver();
   virtual ~ChromeNotificationObserver();
 
-  // Notification handlers:
+  // IPC message handlers:
+  void OnBrowserWindowReady(Browser* browser);
   void OnRendererProcessCreated(content::RenderProcessHost* process);
 
   // content::NotificationObserver overrides:
diff --git a/chrome/browser/extensions/chrome_process_manager_delegate.cc b/chrome/browser/extensions/chrome_process_manager_delegate.cc
deleted file mode 100644
index 12e0c16..0000000
--- a/chrome/browser/extensions/chrome_process_manager_delegate.cc
+++ /dev/null
@@ -1,143 +0,0 @@
-// Copyright 2014 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/extensions/chrome_process_manager_delegate.h"
-
-#include "base/command_line.h"
-#include "base/logging.h"
-#include "chrome/browser/browser_process.h"
-#include "chrome/browser/chrome_notification_types.h"
-#include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/profiles/profile_manager.h"
-#include "chrome/browser/ui/browser.h"
-#include "content/public/browser/notification_service.h"
-#include "extensions/browser/extension_system.h"
-#include "extensions/browser/process_manager.h"
-#include "extensions/common/one_shot_event.h"
-
-#if !defined(OS_ANDROID)
-#include "chrome/browser/ui/browser_finder.h"
-#include "chrome/common/chrome_switches.h"
-#endif
-
-namespace extensions {
-
-ChromeProcessManagerDelegate::ChromeProcessManagerDelegate() {
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_BROWSER_WINDOW_READY,
-                 content::NotificationService::AllSources());
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_PROFILE_CREATED,
-                 content::NotificationService::AllSources());
-  // TODO(jamescook): Move observation of NOTIFICATION_PROFILE_DESTROYED here.
-  // http://crbug.com/392658
-}
-
-ChromeProcessManagerDelegate::~ChromeProcessManagerDelegate() {
-}
-
-bool ChromeProcessManagerDelegate::IsBackgroundPageAllowed(
-    content::BrowserContext* context) const {
-  Profile* profile = static_cast<Profile*>(context);
-
-  // Disallow if the current session is a Guest mode session but the current
-  // browser context is *not* off-the-record. Such context is artificial and
-  // background page shouldn't be created in it.
-  // http://crbug.com/329498
-  return !(profile->IsGuestSession() && !profile->IsOffTheRecord());
-}
-
-bool ChromeProcessManagerDelegate::DeferCreatingStartupBackgroundHosts(
-    content::BrowserContext* context) const {
-  Profile* profile = static_cast<Profile*>(context);
-
-  // The profile may not be valid yet if it is still being initialized.
-  // In that case, defer loading, since it depends on an initialized profile.
-  // Background hosts will be loaded later via NOTIFICATION_PROFILE_CREATED.
-  // http://crbug.com/222473
-  if (!g_browser_process->profile_manager()->IsValidProfile(profile))
-    return true;
-
-#if defined(OS_ANDROID)
-  return false;
-#else
-  // There are no browser windows open and the browser process was
-  // started to show the app launcher. Background hosts will be loaded later
-  // via NOTIFICATION_BROWSER_WINDOW_READY. http://crbug.com/178260
-  return chrome::GetTotalBrowserCountForProfile(profile) == 0 &&
-         CommandLine::ForCurrentProcess()->HasSwitch(switches::kShowAppList);
-#endif
-}
-
-void ChromeProcessManagerDelegate::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  switch (type) {
-    case chrome::NOTIFICATION_BROWSER_WINDOW_READY: {
-      Browser* browser = content::Source<Browser>(source).ptr();
-      OnBrowserWindowReady(browser);
-      break;
-    }
-    case chrome::NOTIFICATION_PROFILE_CREATED: {
-      Profile* profile = content::Source<Profile>(source).ptr();
-      OnProfileCreated(profile);
-      break;
-    }
-
-    default:
-      NOTREACHED();
-  }
-}
-
-void ChromeProcessManagerDelegate::OnBrowserWindowReady(Browser* browser) {
-  Profile* profile = browser->profile();
-  DCHECK(profile);
-
-  // If the extension system isn't ready yet the background hosts will be
-  // created automatically when it is.
-  ExtensionSystem* system = ExtensionSystem::Get(profile);
-  if (!system->ready().is_signaled())
-    return;
-
-  // Inform the process manager for this profile that the window is ready.
-  // We continue to observe the notification in case browser windows open for
-  // a related incognito profile or other regular profiles.
-  ProcessManager* manager = system->process_manager();
-  if (!manager)  // Tests may not have a process manager.
-    return;
-  DCHECK_EQ(profile, manager->GetBrowserContext());
-  manager->MaybeCreateStartupBackgroundHosts();
-
-  // For incognito profiles also inform the original profile's process manager
-  // that the window is ready. This will usually be a no-op because the
-  // original profile's process manager should have been informed when the
-  // non-incognito window opened.
-  if (profile->IsOffTheRecord()) {
-    Profile* original_profile = profile->GetOriginalProfile();
-    ProcessManager* original_manager =
-        ExtensionSystem::Get(original_profile)->process_manager();
-    DCHECK(original_manager);
-    DCHECK_EQ(original_profile, original_manager->GetBrowserContext());
-    original_manager->MaybeCreateStartupBackgroundHosts();
-  }
-}
-
-void ChromeProcessManagerDelegate::OnProfileCreated(Profile* profile) {
-  // Incognito profiles are handled by their original profile.
-  if (profile->IsOffTheRecord())
-    return;
-
-  // The profile can be created before the extension system is ready.
-  ProcessManager* manager = ExtensionSystem::Get(profile)->process_manager();
-  if (!manager)
-    return;
-
-  // The profile might have been initialized asynchronously (in parallel with
-  // extension system startup). Now that initialization is complete the
-  // ProcessManager can load deferred background pages.
-  manager->MaybeCreateStartupBackgroundHosts();
-}
-
-}  // namespace extensions
diff --git a/chrome/browser/extensions/chrome_process_manager_delegate.h b/chrome/browser/extensions/chrome_process_manager_delegate.h
deleted file mode 100644
index 9bcc58a..0000000
--- a/chrome/browser/extensions/chrome_process_manager_delegate.h
+++ /dev/null
@@ -1,50 +0,0 @@
-// Copyright 2014 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.
-
-#ifndef CHROME_BROWSER_EXTENSIONS_CHROME_PROCESS_MANAGER_DELEGATE_H_
-#define CHROME_BROWSER_EXTENSIONS_CHROME_PROCESS_MANAGER_DELEGATE_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
-#include "extensions/browser/process_manager_delegate.h"
-
-class Browser;
-class Profile;
-
-namespace extensions {
-
-// Support for ProcessManager. Controls cases where Chrome wishes to disallow
-// extension background pages or defer their creation.
-class ChromeProcessManagerDelegate : public ProcessManagerDelegate,
-                                     public content::NotificationObserver {
- public:
-  ChromeProcessManagerDelegate();
-  virtual ~ChromeProcessManagerDelegate();
-
-  // ProcessManagerDelegate implementation:
-  virtual bool IsBackgroundPageAllowed(
-      content::BrowserContext* context) const OVERRIDE;
-  virtual bool DeferCreatingStartupBackgroundHosts(
-      content::BrowserContext* context) const OVERRIDE;
-
-  // content::NotificationObserver implementation:
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
- private:
-  // Notification handlers.
-  void OnBrowserWindowReady(Browser* browser);
-  void OnProfileCreated(Profile* profile);
-
-  content::NotificationRegistrar registrar_;
-
-  DISALLOW_COPY_AND_ASSIGN(ChromeProcessManagerDelegate);
-};
-
-}  // namespace extensions
-
-#endif  // CHROME_BROWSER_EXTENSIONS_CHROME_PROCESS_MANAGER_DELEGATE_H_
diff --git a/chrome/chrome_browser_extensions.gypi b/chrome/chrome_browser_extensions.gypi
index 0e955f7..194dab0e 100644
--- a/chrome/chrome_browser_extensions.gypi
+++ b/chrome/chrome_browser_extensions.gypi
@@ -45,8 +45,6 @@
       'browser/extensions/chrome_extensions_browser_client.h',
       'browser/extensions/chrome_notification_observer.cc',
       'browser/extensions/chrome_notification_observer.h',
-      'browser/extensions/chrome_process_manager_delegate.cc',
-      'browser/extensions/chrome_process_manager_delegate.h',
       'browser/extensions/component_loader.cc',
       'browser/extensions/component_loader.h',
       'browser/extensions/context_menu_matcher.cc',
diff --git a/extensions/DEPS b/extensions/DEPS
index 4077a55..0505b02 100644
--- a/extensions/DEPS
+++ b/extensions/DEPS
@@ -1,5 +1,4 @@
 include_rules = [
-  # Do not add Chrome dependencies. Much work went into removing them.
   "+components/url_matcher",
   "+content/public/common",
   "+content/public/test",
@@ -14,7 +13,7 @@ include_rules = [
   # NOTE: Please do not add includes without talking to the app shell team;
   # see OWNERS for this directory.
   #
-  # TODO(jamescook): Remove this. http://crbug.com/392622
+  # TODO(jamescook): Remove these. http://crbug.com/162530
   "!chrome/browser/chrome_notification_types.h",
 ]
 
diff --git a/extensions/browser/extensions_browser_client.h b/extensions/browser/extensions_browser_client.h
index cb810b6..293b2af 100644
--- a/extensions/browser/extensions_browser_client.h
+++ b/extensions/browser/extensions_browser_client.h
@@ -41,7 +41,6 @@ class ExtensionPrefsObserver;
 class ExtensionSystem;
 class ExtensionSystemProvider;
 class InfoMap;
-class ProcessManagerDelegate;
 class RuntimeAPIDelegate;
 
 // Interface to allow the extensions module to make browser-process-specific
@@ -134,9 +133,12 @@ class ExtensionsBrowserClient {
       content::BrowserContext* context,
       std::vector<ExtensionPrefsObserver*>* observers) const = 0;
 
-  // Returns the ProcessManagerDelegate shared across all BrowserContexts. May
-  // return NULL in tests or for simple embedders.
-  virtual ProcessManagerDelegate* GetProcessManagerDelegate() const = 0;
+  // Returns true if loading background pages should be deferred.
+  virtual bool DeferLoadingBackgroundHosts(
+      content::BrowserContext* context) const = 0;
+
+  virtual bool IsBackgroundPageAllowed(
+      content::BrowserContext* context) const = 0;
 
   // Creates a new ExtensionHostDelegate instance.
   virtual scoped_ptr<ExtensionHostDelegate> CreateExtensionHostDelegate() = 0;
diff --git a/extensions/browser/process_manager.cc b/extensions/browser/process_manager.cc
index 12afd7c..e6beddb 100644
--- a/extensions/browser/process_manager.cc
+++ b/extensions/browser/process_manager.cc
@@ -33,7 +33,6 @@
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
-#include "extensions/browser/process_manager_delegate.h"
 #include "extensions/browser/process_manager_observer.h"
 #include "extensions/browser/view_type_utils.h"
 #include "extensions/common/constants.h"
@@ -246,6 +245,8 @@ ProcessManager::ProcessManager(BrowserContext* context,
                  content::NotificationService::AllSources());
   registrar_.Add(this, content::NOTIFICATION_WEB_CONTENTS_CONNECTED,
                  content::NotificationService::AllSources());
+  registrar_.Add(this, chrome::NOTIFICATION_PROFILE_CREATED,
+                 content::Source<BrowserContext>(original_context));
   registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
                  content::Source<BrowserContext>(context));
   if (context->IsOffTheRecord()) {
@@ -306,14 +307,11 @@ bool ProcessManager::CreateBackgroundHost(const Extension* extension,
                                           const GURL& url) {
   // Hosted apps are taken care of from BackgroundContentsService. Ignore them
   // here.
-  if (extension->is_hosted_app())
-    return false;
-
-  // Don't create hosts if the embedder doesn't allow it.
-  ProcessManagerDelegate* delegate =
-      ExtensionsBrowserClient::Get()->GetProcessManagerDelegate();
-  if (delegate && !delegate->IsBackgroundPageAllowed(GetBrowserContext()))
+  if (extension->is_hosted_app() ||
+      !ExtensionsBrowserClient::Get()->
+          IsBackgroundPageAllowed(GetBrowserContext())) {
     return false;
+  }
 
   // Don't create multiple background hosts for an extension.
   if (GetBackgroundHostForExtension(extension->id()))
@@ -622,6 +620,16 @@ void ProcessManager::CancelSuspend(const Extension* extension) {
   }
 }
 
+void ProcessManager::OnBrowserWindowReady() {
+  // If the extension system isn't ready yet the background hosts will be
+  // created via NOTIFICATION_EXTENSIONS_READY below.
+  ExtensionSystem* system = ExtensionSystem::Get(GetBrowserContext());
+  if (!system->ready().is_signaled())
+    return;
+
+  CreateBackgroundHostsForProfileStartup();
+}
+
 content::BrowserContext* ProcessManager::GetBrowserContext() const {
   return site_instance_->GetBrowserContext();
 }
@@ -640,10 +648,15 @@ void ProcessManager::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
   switch (type) {
-    case chrome::NOTIFICATION_EXTENSIONS_READY: {
-      // TODO(jamescook): Convert this to use ExtensionSystem::ready() instead
-      // of a notification.
-      MaybeCreateStartupBackgroundHosts();
+    case chrome::NOTIFICATION_EXTENSIONS_READY:
+    case chrome::NOTIFICATION_PROFILE_CREATED: {
+       // Don't load background hosts now if the loading should be deferred.
+       // Instead they will be loaded when a browser window for this profile
+       // (or an incognito profile from this profile) is ready.
+       if (DeferLoadingBackgroundHosts())
+         break;
+
+      CreateBackgroundHostsForProfileStartup();
       break;
     }
 
@@ -771,24 +784,24 @@ void ProcessManager::OnDevToolsStateChanged(
   }
 }
 
-void ProcessManager::MaybeCreateStartupBackgroundHosts() {
-  if (startup_background_hosts_created_)
-    return;
-
-  // The embedder might disallow background pages entirely.
-  ProcessManagerDelegate* delegate =
-      ExtensionsBrowserClient::Get()->GetProcessManagerDelegate();
-  if (delegate && !delegate->IsBackgroundPageAllowed(GetBrowserContext()))
+void ProcessManager::CreateBackgroundHostsForProfileStartup() {
+  if (startup_background_hosts_created_ ||
+      !ExtensionsBrowserClient::Get()->
+          IsBackgroundPageAllowed(GetBrowserContext())) {
     return;
+  }
 
-  // The embedder might want to defer background page loading. For example,
-  // Chrome defers background page loading when it is launched to show the app
-  // list, then triggers a load later when a browser window opens.
-  if (delegate &&
-      delegate->DeferCreatingStartupBackgroundHosts(GetBrowserContext()))
-    return;
+  const ExtensionSet& enabled_extensions =
+      ExtensionRegistry::Get(GetBrowserContext())->enabled_extensions();
+  for (ExtensionSet::const_iterator extension = enabled_extensions.begin();
+       extension != enabled_extensions.end();
+       ++extension) {
+    CreateBackgroundHostForExtensionLoad(this, extension->get());
 
-  CreateStartupBackgroundHosts();
+    FOR_EACH_OBSERVER(ProcessManagerObserver,
+                      observer_list_,
+                      OnBackgroundHostStartup(*extension));
+  }
   startup_background_hosts_created_ = true;
 
   // Background pages should only be loaded once. To prevent any further loads
@@ -797,6 +810,14 @@ void ProcessManager::MaybeCreateStartupBackgroundHosts() {
       ExtensionsBrowserClient::Get()->GetOriginalContext(GetBrowserContext());
   if (registrar_.IsRegistered(
           this,
+          chrome::NOTIFICATION_PROFILE_CREATED,
+          content::Source<BrowserContext>(original_context))) {
+    registrar_.Remove(this,
+                      chrome::NOTIFICATION_PROFILE_CREATED,
+                      content::Source<BrowserContext>(original_context));
+  }
+  if (registrar_.IsRegistered(
+          this,
           chrome::NOTIFICATION_EXTENSIONS_READY,
           content::Source<BrowserContext>(original_context))) {
     registrar_.Remove(this,
@@ -805,21 +826,6 @@ void ProcessManager::MaybeCreateStartupBackgroundHosts() {
   }
 }
 
-void ProcessManager::CreateStartupBackgroundHosts() {
-  DCHECK(!startup_background_hosts_created_);
-  const ExtensionSet& enabled_extensions =
-      ExtensionRegistry::Get(GetBrowserContext())->enabled_extensions();
-  for (ExtensionSet::const_iterator extension = enabled_extensions.begin();
-       extension != enabled_extensions.end();
-       ++extension) {
-    CreateBackgroundHostForExtensionLoad(this, extension->get());
-
-    FOR_EACH_OBSERVER(ProcessManagerObserver,
-                      observer_list_,
-                      OnBackgroundHostStartup(*extension));
-  }
-}
-
 void ProcessManager::OnBackgroundHostCreated(ExtensionHost* host) {
   DCHECK_EQ(GetBrowserContext(), host->browser_context());
   background_hosts_.insert(host);
@@ -884,6 +890,12 @@ void ProcessManager::ClearBackgroundPageData(const std::string& extension_id) {
   }
 }
 
+bool ProcessManager::DeferLoadingBackgroundHosts() const {
+  // The extensions embedder may have special rules about background hosts.
+  return ExtensionsBrowserClient::Get()->DeferLoadingBackgroundHosts(
+      GetBrowserContext());
+}
+
 //
 // IncognitoProcessManager
 //
@@ -902,6 +914,8 @@ IncognitoProcessManager::IncognitoProcessManager(
   // in the NOTIFICATION_BROWSER_WINDOW_READY notification handler.
   registrar_.Remove(this, chrome::NOTIFICATION_EXTENSIONS_READY,
                     content::Source<BrowserContext>(original_context));
+  registrar_.Remove(this, chrome::NOTIFICATION_PROFILE_CREATED,
+                    content::Source<BrowserContext>(original_context));
 }
 
 bool IncognitoProcessManager::CreateBackgroundHost(const Extension* extension,
diff --git a/extensions/browser/process_manager.h b/extensions/browser/process_manager.h
index 80736e4..e580bbd 100644
--- a/extensions/browser/process_manager.h
+++ b/extensions/browser/process_manager.h
@@ -33,7 +33,6 @@ namespace extensions {
 
 class Extension;
 class ExtensionHost;
-class ProcessManagerDelegate;
 class ProcessManagerObserver;
 
 // Manages dynamic state of running Chromium extensions. There is one instance
@@ -123,9 +122,8 @@ class ProcessManager : public content::NotificationObserver {
   // onSuspendCanceled() event to it.
   void CancelSuspend(const Extension* extension);
 
-  // Creates background hosts if the embedder is ready and they are not already
-  // loaded.
-  void MaybeCreateStartupBackgroundHosts();
+  // Ensures background hosts are loaded for a new browser window.
+  void OnBrowserWindowReady();
 
   // Gets the BrowserContext associated with site_instance_ and all other
   // related SiteInstances.
@@ -146,10 +144,6 @@ class ProcessManager : public content::NotificationObserver {
       content::BrowserContext* original_context,
       ProcessManager* original_manager);
 
-  bool startup_background_hosts_created_for_test() const {
-    return startup_background_hosts_created_;
-  }
-
  protected:
   // If |context| is incognito pass the master context as |original_context|.
   // Otherwise pass the same context for both.
@@ -164,6 +158,10 @@ class ProcessManager : public content::NotificationObserver {
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Load all background pages once the profile data is ready and the pages
+  // should be loaded.
+  void CreateBackgroundHostsForProfileStartup();
+
   content::NotificationRegistrar registrar_;
 
   // The set of ExtensionHosts running viewless background extensions.
@@ -184,10 +182,6 @@ class ProcessManager : public content::NotificationObserver {
   typedef std::map<content::RenderViewHost*,
       extensions::ViewType> ExtensionRenderViews;
 
-  // Load all background pages once the profile data is ready and the pages
-  // should be loaded.
-  void CreateStartupBackgroundHosts();
-
   // Called just after |host| is created so it can be registered in our lists.
   void OnBackgroundHostCreated(ExtensionHost* host);
 
@@ -222,6 +216,9 @@ class ProcessManager : public content::NotificationObserver {
   // Clears background page data for this extension.
   void ClearBackgroundPageData(const std::string& extension_id);
 
+  // Returns true if loading background pages should be deferred.
+  bool DeferLoadingBackgroundHosts() const;
+
   void OnDevToolsStateChanged(content::DevToolsAgentHost*, bool attached);
 
   // Contains all active extension-related RenderViewHost instances for all
diff --git a/extensions/browser/process_manager_delegate.h b/extensions/browser/process_manager_delegate.h
deleted file mode 100644
index 7cc48c0..0000000
--- a/extensions/browser/process_manager_delegate.h
+++ /dev/null
@@ -1,34 +0,0 @@
-// Copyright 2014 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.
-
-#ifndef EXTENSIONS_BROWSER_PROCESS_MANAGER_DELEGATE_H_
-#define EXTENSIONS_BROWSER_PROCESS_MANAGER_DELEGATE_H_
-
-namespace content {
-class BrowserContext;
-};
-
-namespace extensions {
-
-// Customization of ProcessManager for the extension system embedder.
-class ProcessManagerDelegate {
- public:
-  virtual ~ProcessManagerDelegate() {}
-
-  // Returns true if the embedder allows background pages for the given
-  // |context|.
-  virtual bool IsBackgroundPageAllowed(
-      content::BrowserContext* context) const = 0;
-
-  // Returns true if the embedder wishes to defer starting up the renderers for
-  // extension background pages. If the embedder returns true it must call
-  // ProcessManager::MaybeCreateStartupBackgroundHosts() when it is ready. See
-  // ChromeProcessManagerDelegate for examples of how this is useful.
-  virtual bool DeferCreatingStartupBackgroundHosts(
-      content::BrowserContext* context) const = 0;
-};
-
-}  // namespace extensions
-
-#endif  // EXTENSIONS_BROWSER_PROCESS_MANAGER_DELEGATE_H_
diff --git a/extensions/browser/process_manager_unittest.cc b/extensions/browser/process_manager_unittest.cc
index 0d1f86b..b72b112 100644
--- a/extensions/browser/process_manager_unittest.cc
+++ b/extensions/browser/process_manager_unittest.cc
@@ -5,12 +5,10 @@
 #include "extensions/browser/process_manager.h"
 
 #include "chrome/browser/chrome_notification_types.h"
-#include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/test/test_browser_context.h"
-#include "extensions/browser/process_manager_delegate.h"
 #include "extensions/browser/test_extensions_browser_client.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -35,35 +33,12 @@ class TestBrowserContextIncognito : public TestBrowserContext {
   DISALLOW_COPY_AND_ASSIGN(TestBrowserContextIncognito);
 };
 
-// A trivial ProcessManagerDelegate.
-class TestProcessManagerDelegate : public ProcessManagerDelegate {
- public:
-  TestProcessManagerDelegate()
-      : is_background_page_allowed_(true),
-        defer_creating_startup_background_hosts_(false) {}
-  virtual ~TestProcessManagerDelegate() {}
-
-  // ProcessManagerDelegate implementation.
-  virtual bool IsBackgroundPageAllowed(BrowserContext* context) const OVERRIDE {
-    return is_background_page_allowed_;
-  }
-  virtual bool DeferCreatingStartupBackgroundHosts(
-      BrowserContext* context) const OVERRIDE {
-    return defer_creating_startup_background_hosts_;
-  }
-
-  bool is_background_page_allowed_;
-  bool defer_creating_startup_background_hosts_;
-};
-
 }  // namespace
 
 class ProcessManagerTest : public testing::Test {
  public:
   ProcessManagerTest() : extensions_browser_client_(&original_context_) {
     extensions_browser_client_.SetIncognitoContext(&incognito_context_);
-    extensions_browser_client_.set_process_manager_delegate(
-        &process_manager_delegate_);
     ExtensionsBrowserClient::Set(&extensions_browser_client_);
   }
 
@@ -74,23 +49,6 @@ class ProcessManagerTest : public testing::Test {
   BrowserContext* original_context() { return &original_context_; }
   BrowserContext* incognito_context() { return &incognito_context_; }
 
-  // testing::Test implementation.
-  virtual void SetUp() OVERRIDE {
-    // Needed for ExtensionRegistry.
-    BrowserContextDependencyManager::GetInstance()
-        ->CreateBrowserContextServicesForTest(&original_context_);
-    BrowserContextDependencyManager::GetInstance()
-        ->CreateBrowserContextServicesForTest(&incognito_context_);
-  }
-
-  virtual void TearDown() OVERRIDE {
-    // Needed to clean up ExtensionRegistry.
-    BrowserContextDependencyManager::GetInstance()
-        ->DestroyBrowserContextServices(&incognito_context_);
-    BrowserContextDependencyManager::GetInstance()
-        ->DestroyBrowserContextServices(&original_context_);
-  }
-
   // Returns true if the notification |type| is registered for |manager| with
   // source |context|. Pass NULL for |context| for all sources.
   static bool IsRegistered(ProcessManager* manager,
@@ -100,10 +58,9 @@ class ProcessManagerTest : public testing::Test {
         manager, type, content::Source<BrowserContext>(context));
   }
 
- protected:
+ private:
   TestBrowserContext original_context_;
   TestBrowserContextIncognito incognito_context_;
-  TestProcessManagerDelegate process_manager_delegate_;
   TestExtensionsBrowserClient extensions_browser_client_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessManagerTest);
@@ -168,83 +125,6 @@ TEST_F(ProcessManagerTest, ExtensionNotificationRegistration) {
                            incognito_context()));
 }
 
-// Test that startup background hosts are created when the extension system
-// becomes ready.
-//
-// NOTE: This test and those that follow do not try to create ExtensionsHosts
-// because ExtensionHost is tightly coupled to WebContents and can't be
-// constructed in unit tests.
-TEST_F(ProcessManagerTest, CreateBackgroundHostsOnExtensionsReady) {
-  scoped_ptr<ProcessManager> manager(
-      ProcessManager::Create(original_context()));
-  ASSERT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // Simulate the extension system becoming ready.
-  content::NotificationService::current()->Notify(
-      chrome::NOTIFICATION_EXTENSIONS_READY,
-      content::Source<BrowserContext>(original_context()),
-      content::NotificationService::NoDetails());
-  EXPECT_TRUE(manager->startup_background_hosts_created_for_test());
-}
-
-// Test that startup background hosts can be created explicitly before the
-// extension system is ready (this is the normal pattern in Chrome).
-TEST_F(ProcessManagerTest, CreateBackgroundHostsExplicitly) {
-  scoped_ptr<ProcessManager> manager(
-      ProcessManager::Create(original_context()));
-  ASSERT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // Embedder explicitly asks for hosts to be created. Chrome does this on
-  // normal startup.
-  manager->MaybeCreateStartupBackgroundHosts();
-  EXPECT_TRUE(manager->startup_background_hosts_created_for_test());
-}
-
-// Test that the embedder can defer background host creation. Chrome does this
-// when the profile is created asynchronously, which may take a while.
-TEST_F(ProcessManagerTest, CreateBackgroundHostsDeferred) {
-  scoped_ptr<ProcessManager> manager(
-      ProcessManager::Create(original_context()));
-  ASSERT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // Don't create background hosts if the delegate says to defer them.
-  process_manager_delegate_.defer_creating_startup_background_hosts_ = true;
-  manager->MaybeCreateStartupBackgroundHosts();
-  EXPECT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // The extension system becoming ready still doesn't create the hosts.
-  content::NotificationService::current()->Notify(
-      chrome::NOTIFICATION_EXTENSIONS_READY,
-      content::Source<BrowserContext>(original_context()),
-      content::NotificationService::NoDetails());
-  EXPECT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // Once the embedder is ready the background hosts can be created.
-  process_manager_delegate_.defer_creating_startup_background_hosts_ = false;
-  manager->MaybeCreateStartupBackgroundHosts();
-  EXPECT_TRUE(manager->startup_background_hosts_created_for_test());
-}
-
-// Test that the embedder can disallow background host creation.
-// Chrome OS does this in guest mode.
-TEST_F(ProcessManagerTest, IsBackgroundHostAllowed) {
-  scoped_ptr<ProcessManager> manager(
-      ProcessManager::Create(original_context()));
-  ASSERT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // Don't create background hosts if the delegate disallows them.
-  process_manager_delegate_.is_background_page_allowed_ = false;
-  manager->MaybeCreateStartupBackgroundHosts();
-  EXPECT_FALSE(manager->startup_background_hosts_created_for_test());
-
-  // The extension system becoming ready still doesn't create the hosts.
-  content::NotificationService::current()->Notify(
-      chrome::NOTIFICATION_EXTENSIONS_READY,
-      content::Source<BrowserContext>(original_context()),
-      content::NotificationService::NoDetails());
-  EXPECT_FALSE(manager->startup_background_hosts_created_for_test());
-}
-
 // Test that extensions get grouped in the right SiteInstance (and therefore
 // process) based on their URLs.
 TEST_F(ProcessManagerTest, ProcessGrouping) {
diff --git a/extensions/browser/test_extensions_browser_client.cc b/extensions/browser/test_extensions_browser_client.cc
index a01b128..dcd467f 100644
--- a/extensions/browser/test_extensions_browser_client.cc
+++ b/extensions/browser/test_extensions_browser_client.cc
@@ -15,9 +15,7 @@ namespace extensions {
 
 TestExtensionsBrowserClient::TestExtensionsBrowserClient(
     BrowserContext* main_context)
-    : main_context_(main_context),
-      incognito_context_(NULL),
-      process_manager_delegate_(NULL) {
+    : main_context_(main_context), incognito_context_(NULL) {
   DCHECK(main_context_);
   DCHECK(!main_context_->IsOffTheRecord());
 }
@@ -118,9 +116,14 @@ void TestExtensionsBrowserClient::GetEarlyExtensionPrefsObservers(
     content::BrowserContext* context,
     std::vector<ExtensionPrefsObserver*>* observers) const {}
 
-ProcessManagerDelegate* TestExtensionsBrowserClient::GetProcessManagerDelegate()
-    const {
-  return process_manager_delegate_;
+bool TestExtensionsBrowserClient::DeferLoadingBackgroundHosts(
+    BrowserContext* context) const {
+  return false;
+}
+
+bool TestExtensionsBrowserClient::IsBackgroundPageAllowed(
+    BrowserContext* context) const {
+  return true;
 }
 
 scoped_ptr<ExtensionHostDelegate>
diff --git a/extensions/browser/test_extensions_browser_client.h b/extensions/browser/test_extensions_browser_client.h
index 1cfffee..b793259 100644
--- a/extensions/browser/test_extensions_browser_client.h
+++ b/extensions/browser/test_extensions_browser_client.h
@@ -15,14 +15,10 @@ namespace extensions {
 // this class should call ExtensionsBrowserClient::Set() with its instance.
 class TestExtensionsBrowserClient : public ExtensionsBrowserClient {
  public:
-  // |main_context| is required and must not be an incognito context.
+  // |context| is required and must not be an incognito context.
   explicit TestExtensionsBrowserClient(content::BrowserContext* main_context);
   virtual ~TestExtensionsBrowserClient();
 
-  void set_process_manager_delegate(ProcessManagerDelegate* delegate) {
-    process_manager_delegate_ = delegate;
-  }
-
   // Associates an incognito context with |main_context_|.
   void SetIncognitoContext(content::BrowserContext* incognito_context);
 
@@ -63,7 +59,10 @@ class TestExtensionsBrowserClient : public ExtensionsBrowserClient {
   virtual void GetEarlyExtensionPrefsObservers(
       content::BrowserContext* context,
       std::vector<ExtensionPrefsObserver*>* observers) const OVERRIDE;
-  virtual ProcessManagerDelegate* GetProcessManagerDelegate() const OVERRIDE;
+  virtual bool DeferLoadingBackgroundHosts(
+      content::BrowserContext* context) const OVERRIDE;
+  virtual bool IsBackgroundPageAllowed(content::BrowserContext* context) const
+      OVERRIDE;
   virtual scoped_ptr<ExtensionHostDelegate> CreateExtensionHostDelegate()
       OVERRIDE;
   virtual bool DidVersionUpdate(content::BrowserContext* context) OVERRIDE;
@@ -83,9 +82,6 @@ class TestExtensionsBrowserClient : public ExtensionsBrowserClient {
   content::BrowserContext* main_context_;       // Not owned.
   content::BrowserContext* incognito_context_;  // Not owned, defaults to NULL.
 
-  // Not owned, defaults to NULL.
-  ProcessManagerDelegate* process_manager_delegate_;
-
   DISALLOW_COPY_AND_ASSIGN(TestExtensionsBrowserClient);
 };
 
diff --git a/extensions/extensions.gyp b/extensions/extensions.gyp
index 3501961..4349183 100644
--- a/extensions/extensions.gyp
+++ b/extensions/extensions.gyp
@@ -435,7 +435,6 @@
         'browser/pref_names.h',
         'browser/process_manager.cc',
         'browser/process_manager.h',
-        'browser/process_manager_delegate.h',
         'browser/process_manager_observer.h',
         'browser/process_map.cc',
         'browser/process_map.h',