Add a specialized apps::NativeAppWindow for app_shell

apps/shell_window.cc

Index: apps/shell_window.cc
diff --git a/apps/shell_window.cc b/apps/shell_window.cc
index 8bb62623e231de04344e6bd5f5eab11dc5221bc4..a188a9a2ffef80d52c61ef85e8f9f6b70438d892 100644
--- a/apps/shell_window.cc
+++ b/apps/shell_window.cc
@@ -4,6 +4,7 @@
 
 #include "apps/shell_window.h"
 
+#include "apps/apps_client.h"
 #include "apps/shell_window_geometry_cache.h"
 #include "apps/shell_window_registry.h"
 #include "apps/ui/native_app_window.h"
@@ -14,7 +15,6 @@
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_web_contents_observer.h"
 #include "chrome/browser/extensions/suggest_permission_util.h"
-#include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_messages.h"
 #include "chrome/common/extensions/manifest_handlers/icons_handler.h"
@@ -233,7 +233,7 @@ void ShellWindow::Init(const GURL& url,
   }
 
   // Prevent the browser process from shutting down while this window is open.
-  chrome::StartKeepAlive();
+  AppsClient::Get()->StartKeepAlive();
 
   UpdateExtensionAppIcon();
 
@@ -246,7 +246,7 @@ ShellWindow::~ShellWindow() {
   registrar_.RemoveAll();
 
   // Remove shutdown prevention.
-  chrome::EndKeepAlive();
+  AppsClient::Get()->EndKeepAlive();
 }
 
 void ShellWindow::RequestMediaAccessPermission(