Keep browser process alive while there are platform apps with background pages running.

chrome/browser/extensions/extension_host.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 "chrome/browser/extensions/extension_host.h"
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/memory/singleton.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/browser_shutdown.h"
 #include "chrome/browser/extensions/event_router.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/extensions/extension_tab_util.h"
 #include "chrome/browser/extensions/window_controller.h"
 #include "chrome/browser/file_select_helper.h"
+#include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/app_modal_dialogs/javascript_dialog_creator.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/prefs/prefs_tab_helper.h"
 #include "chrome/browser/ui/tab_contents/tab_contents.h"
 #include "chrome/browser/view_type_utils.h"
 #include "chrome/common/chrome_constants.h"
@@ skipping 113 matching lines @@
   chrome::SetViewType(host_contents_.get(), host_type);
 
   PrefsTabHelper::CreateForWebContents(host_contents());
 
   render_view_host_ = host_contents_->GetRenderViewHost();
 
   // Listen for when an extension is unloaded from the same profile, as it may
   // be the same extension that this points to.
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
                  content::Source<Profile>(profile_));
+
+  // Keep the browser process alive while platform apps have active background
+  // pages.
+  if (extension_->is_platform_app() &&
+      extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_BACKGROUND_PAGE) {

[benwells, 2012/10/12 05:33:38]

I don't like putting the is_platform_app check here. This is the only difference
so far for platform apps in the background page behavior.

Also, the extension_host_type check is strictly unnecessary but it feels less
fragile / scary with it in.

[Aaron Boodman, 2012/10/12 17:58:30]

What about if ExtensionHost supported this feature as a property:

extension_host->set_keeps_browser_alive(true)

Would there be a natural app-specific place to call this?

+    browser::StartKeepAlive();
+  }
 }
 
 ExtensionHost::~ExtensionHost() {
   if (extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_BACKGROUND_PAGE &&
       extension_ && extension_->has_lazy_background_page()) {
     UMA_HISTOGRAM_LONG_TIMES("Extensions.EventPageActiveTime",
                              since_created_.Elapsed());
   }
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_EXTENSION_HOST_DESTROYED,
       content::Source<Profile>(profile_),
       content::Details<ExtensionHost>(this));
   ProcessCreationQueue::GetInstance()->Remove(this);
+
+  if (extension_->is_platform_app() &&
+      extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_BACKGROUND_PAGE) {
+    browser::EndKeepAlive();
+  }
 }
 
 void ExtensionHost::CreateView(Browser* browser) {
 #if defined(TOOLKIT_VIEWS)
   view_.reset(new ExtensionViewViews(this, browser));
   // We own |view_|, so don't auto delete when it's removed from the view
   // hierarchy.
   view_->set_owned_by_client();
 #elif defined(OS_MACOSX)
   view_.reset(new ExtensionViewMac(this, browser));
@@ skipping 454 matching lines @@
 }
 
 void ExtensionHost::RenderViewReady() {
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_EXTENSION_HOST_CREATED,
       content::Source<Profile>(profile_),
       content::Details<ExtensionHost>(this));
 }
 
 }  // namespace extensions