Android: stash the binding status in ChildProcessConnection upon disconnection.

This patch makes ChildProcessConnection stash the status of its oom bindings
when the connection disconnects (closes unexpectedly) and exposes this status
in ChildProcessConnection::isOomProtectedOrWasWhenDied(). This value in turn is
stashed in the BindingManager when the connection reference is cleared.

These two layers of stashing ensure that queries about the oom binding status
are answered correctly on every stage of renderer crash, including after the
connection is cleared and removed from ChildProcessLauncher.

In return we can drop counting of the oom bindings in BindingManager -
eliminating duplication and simplifying the logic.

BUG=294947

Review URL: https://codereview.chromium.org/102303002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239134 0039d316-1c4b-4281-b951-d872f2087c98