Reland: Refactor code that defers extension background page loading

extensions/browser/process_manager.cc

 // Copyright 2013 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 "extensions/browser/process_manager.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 15 matching lines @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "content/public/common/renderer_preferences.h"
 #include "content/public/common/url_constants.h"
 #include "extensions/browser/extension_host.h"
 #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"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_messages.h"
 #include "extensions/common/manifest_handlers/background_info.h"
 #include "extensions/common/manifest_handlers/incognito_info.h"
 #include "extensions/common/one_shot_event.h"
 #include "extensions/common/switches.h"
 
@@ skipping 192 matching lines @@
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
                  content::Source<BrowserContext>(original_context));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_HOST_DESTROYED,
                  content::Source<BrowserContext>(context));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_HOST_VIEW_SHOULD_CLOSE,
                  content::Source<BrowserContext>(context));
   registrar_.Add(this, content::NOTIFICATION_RENDER_VIEW_HOST_CHANGED,
                  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()) {
     registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
                    content::Source<BrowserContext>(original_context));
   }
 
   // Note: event_page_idle_time_ must be sufficiently larger (e.g. 2x) than
   // kKeepaliveThrottleIntervalInSeconds in ppapi/proxy/plugin_globals.
   event_page_idle_time_ = base::TimeDelta::FromSeconds(10);
@@ skipping 40 matching lines @@
 }
 
 void ProcessManager::RemoveObserver(ProcessManagerObserver* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
 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() ||
-      !ExtensionsBrowserClient::Get()->
-          IsBackgroundPageAllowed(GetBrowserContext())) {
+  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()))
+    return false;
 
   // Don't create multiple background hosts for an extension.
   if (GetBackgroundHostForExtension(extension->id()))
     return true;  // TODO(kalman): return false here? It might break things...
 
   ExtensionHost* host =
       new ExtensionHost(extension, GetSiteInstanceForURL(url), url,
                         VIEW_TYPE_EXTENSION_BACKGROUND_PAGE);
   host->CreateRenderViewSoon();
   OnBackgroundHostCreated(host);
@@ skipping 29 matching lines @@
 
   return result;
 }
 
 const Extension* ProcessManager::GetExtensionForRenderViewHost(
     RenderViewHost* render_view_host) {
   if (!render_view_host->GetSiteInstance())
     return NULL;
 
   ExtensionRegistry* registry = ExtensionRegistry::Get(GetBrowserContext());
   if (!registry)

[James Cook, 2014/07/19 00:19:47]

It turns out in both tests and production code we always have an
ExtensionRegistry, so we can skip a couple if() blocks here and below.

     return NULL;
 
   return registry->enabled_extensions().GetByID(
       GetExtensionID(render_view_host));
 }
 
 void ProcessManager::UnregisterRenderViewHost(
     RenderViewHost* render_view_host) {
   ExtensionRenderViews::iterator view =
       all_extension_views_.find(render_view_host);
@@ skipping 238 matching lines @@
         new ExtensionMsg_CancelSuspend(extension->id()));
     // This increment / decrement is to simulate an instantaneous event. This
     // has the effect of invalidating close_sequence_id, preventing any in
     // progress closes from completing and starting a new close process if
     // necessary.
     IncrementLazyKeepaliveCount(extension);
     DecrementLazyKeepaliveCount(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();
 }
 
 void ProcessManager::SetKeepaliveImpulseCallbackForTesting(
     const ImpulseCallbackForTesting& callback) {
   keepalive_impulse_callback_for_testing_ = callback;
 }
 
 void ProcessManager::SetKeepaliveImpulseDecrementCallbackForTesting(
     const ImpulseCallbackForTesting& callback) {
   keepalive_impulse_decrement_callback_for_testing_ = callback;
 }
 
 void ProcessManager::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
   switch (type) {
-    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();
+    case chrome::NOTIFICATION_EXTENSIONS_READY: {
+      // TODO(jamescook): Convert this to use ExtensionSystem::ready() instead
+      // of a notification.
+      MaybeCreateStartupBackgroundHosts();
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED: {
       BrowserContext* context = content::Source<BrowserContext>(source).ptr();
       ExtensionSystem* system = ExtensionSystem::Get(context);
       if (system->ready().is_signaled()) {
         // The extension system is ready, so create the background host.
         const Extension* extension =
             content::Details<const Extension>(details).ptr();
@@ skipping 107 matching lines @@
     return;
   if (attached) {
     // Keep the lazy background page alive while it's being inspected.
     CancelSuspend(extension);
     IncrementLazyKeepaliveCount(extension);
   } else {
     DecrementLazyKeepaliveCount(extension);
   }
 }
 
-void ProcessManager::CreateBackgroundHostsForProfileStartup() {
-  if (startup_background_hosts_created_ ||
-      !ExtensionsBrowserClient::Get()->
-          IsBackgroundPageAllowed(GetBrowserContext())) {
+void ProcessManager::MaybeCreateStartupBackgroundHosts() {
+  if (startup_background_hosts_created_)
     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());
+  // The embedder might disallow background pages entirely.
+  ProcessManagerDelegate* delegate =
+      ExtensionsBrowserClient::Get()->GetProcessManagerDelegate();
+  if (delegate && !delegate->IsBackgroundPageAllowed(GetBrowserContext()))
+    return;
 
-    FOR_EACH_OBSERVER(ProcessManagerObserver,
-                      observer_list_,
-                      OnBackgroundHostStartup(*extension));
-  }
+  // 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;
+
+  CreateStartupBackgroundHosts();
   startup_background_hosts_created_ = true;
 
   // Background pages should only be loaded once. To prevent any further loads
   // occurring, we remove the notification listeners.
   BrowserContext* original_context =
       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,
                       chrome::NOTIFICATION_EXTENSIONS_READY,
                       content::Source<BrowserContext>(original_context));
   }
 }
 
+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);
 
   if (BackgroundInfo::HasLazyBackgroundPage(host->extension())) {
     linked_ptr<base::ElapsedTimer> since_suspended(
         background_page_data_[host->extension()->id()].
             since_suspended.release());
     if (since_suspended.get()) {
       UMA_HISTOGRAM_LONG_TIMES("Extensions.EventPageIdleTime",
@@ skipping 44 matching lines @@
   // Re-register all RenderViews for this extension. We do this to restore
   // the lazy_keepalive_count (if any) to properly reflect the number of open
   // views.
   for (ExtensionRenderViews::const_iterator it = all_extension_views_.begin();
        it != all_extension_views_.end(); ++it) {
     if (GetExtensionID(it->first) == extension_id)
       IncrementLazyKeepaliveCountForView(it->first);
   }
 }
 
-bool ProcessManager::DeferLoadingBackgroundHosts() const {
-  // The extensions embedder may have special rules about background hosts.
-  return ExtensionsBrowserClient::Get()->DeferLoadingBackgroundHosts(
-      GetBrowserContext());
-}
-
 //
 // IncognitoProcessManager
 //
 
 IncognitoProcessManager::IncognitoProcessManager(
     BrowserContext* incognito_context,
     BrowserContext* original_context,
     ProcessManager* original_manager)
     : ProcessManager(incognito_context, original_context),
       original_manager_(original_manager) {
   DCHECK(incognito_context->IsOffTheRecord());
 
   // The original profile will have its own ProcessManager to
   // load the background pages of the spanning extensions. This process
   // manager need only worry about the split mode extensions, which is handled
   // 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,
                                                    const GURL& url) {
   if (IncognitoInfo::IsSplitMode(extension)) {
     if (ExtensionsBrowserClient::Get()->IsExtensionIncognitoEnabled(
             extension->id(), GetBrowserContext()))
       return ProcessManager::CreateBackgroundHost(extension, url);
   } else {
     // Do nothing. If an extension is spanning, then its original-profile
     // background page is shared with incognito, so we don't create another.
   }
   return false;
 }
 
 SiteInstance* IncognitoProcessManager::GetSiteInstanceForURL(const GURL& url) {
   ExtensionRegistry* registry = ExtensionRegistry::Get(GetBrowserContext());
   if (registry) {
     const Extension* extension =
         registry->enabled_extensions().GetExtensionOrAppByURL(url);
     if (extension && !IncognitoInfo::IsSplitMode(extension)) {
       return original_manager_->GetSiteInstanceForURL(url);
     }
   }
   return ProcessManager::GetSiteInstanceForURL(url);
 }
 
 }  // namespace extensions