Apply automatic enum range checking for appcache enums acros IPC.

This is part of a long-running background task to remove the remaining
uses of the unchecked IPC_ENUM_TRAITS() macro.

BUG=246708

Review URL: https://codereview.chromium.org/149073002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247905 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247905
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
SVN changes up to revision 247906