Ensure the Desktop App Launcher warmup window is not created while trying to quit.

When relaunching from Metro there is a lengthier time-window where
BrowserProcess::IsShuttingDown() is false, but 
browser_shutdown::IsTryingToQuit() is true. If the app launcher delayed
warmup (and the non-delayed asynchronous profile load it triggers) is
unlucky enough to get scheduled here, then it can create a window after
Widget::CloseAllSecondaryWidgets() has been called on the shutdown path,
which otherwise would have mopped up the app launcher resources.

Checking browser_shutdown::IsTryingToQuit ensures the app launcher
window won't be created after Widget::CloseAllSecondaryWidgets() would
have been called during shutdown.

BUG=333350

Review URL: https://codereview.chromium.org/149323002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247906 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/views/app_list/win/app_list_service_win.cc

@@ -23,6 +23,7 @@
 #include "base/win/windows_version.h"
 #include "chrome/app/chrome_dll_resource.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/browser_shutdown.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
@@ -507,8 +508,10 @@ void AppListServiceWin::ScheduleWarmup() {
 }
 
 bool AppListServiceWin::IsWarmupNeeded() {
-  if (!g_browser_process || g_browser_process->IsShuttingDown())
+  if (!g_browser_process || g_browser_process->IsShuttingDown() ||
+      browser_shutdown::IsTryingToQuit()) {
     return false;
+  }
 
   // We only need to initialize the view if there's no view already created and
   // there's no profile loading to be shown.