Ensure the wedge timer isn't started until after StartStream().

Otherwise, in rare conditions, a very long StartStream() may
incorrectly cause a wedge to be flagged.

If StartStream() hangs the message loop is blocked and the timer
will never run anyways.

Also, increase wedge timer to 5 seconds.

BUG=160920
TEST=none

Review URL: https://codereview.chromium.org/64493003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233843 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233843