Propagate the user gesture state. It is necessary to do correct pop-up blocking

      if a plug-in tries to open an URL in a new frame.
No behaviour changes yet -- those require a separate change to the WebKit
chromium directory, that uses the propagated state.

BUG=70538
TEST=NONE

Review URL: http://codereview.chromium.org/6392042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@73417 0039d316-1c4b-4281-b951-d872f2087c98