Move watchlist generation out of RunHooks so that bypass-hooks
does not skip watchlists.

BUG=163406


Review URL: https://chromiumcodereview.appspot.com/12295004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@185979 0039d316-1c4b-4281-b951-d872f2087c98