Make ApplicationImpl::Shutdown not a static and instead have callers use the current object.
The reason is that we'll need to do bookkeeping when an application requests shutdown because there are no outstanding connections. This will involve a handshake with the shell, and we need a place to store state. That should be ApplicationImpl. To do that, we'll need to have the pointer to it at shutdown.
BUG=484234
Review URL: https://codereview.chromium.org/
1157683002
Cr-Commit-Position: refs/heads/master@{#331193}