PreTarget accelerator handler should only be for one FocusManager

Previously, the PreTargetHandler would send the key event to the
FocusManager associated with the widget at creation time. When
there's a transient open, the events should only be sent to the
FocusManager associated with that transient, not to the main
one.

BUG=304754, 305082, 316064
TEST=with --disable-dwm-composition, tab, f11, ctrl-f in main page, dialogs, bubbles.
R=ben@chromium.org

Review URL: https://codereview.chromium.org/62713004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234187 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234187