[Password Autofill] Catch XHR submitted forms where onsubmit() isn't called.

This fixes a bug where the password manager would fail to trigger on the registration form for Facebook.com. The password manager will still fail for synchonous XHR, but
this should be less prevalent.

BUG=43219
R=vabr@chromium.org

Review URL: https://codereview.chromium.org/137893009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246421 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246421
Build with configuration_policy enabled on iOS by default.

This will start covering the policy iOS build on the main waterfall. The code
in chrome/browser/policy is still disabled on that platform by default, but
the policy component and its unittests will be built.

This change also enables one policy on iOS, otherwise some parts of the build
break.

BUG=275292

Review URL: https://codereview.chromium.org/132233031

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246422 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246422