Close Views web contents modal dialogs on interstitial pages by default

All Views web contents modal dialogs have been configured to close on
interstitial pages (e.g. SSL errors) for a while now without issue. This
changes the default to close the dialogs so that each dialog doesn't
have to explicitly specify.

Also change the name of the function, since the interstitial pages are
not technically WebUI, but a blink-generated interstitial page.

BUG=295897

Review URL: https://codereview.chromium.org/35153011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230893 0039d316-1c4b-4281-b951-d872f2087c98
Hide the swipe selection feature behind a flag, --enable-swipe-selection.

We do this in a simple manner by making the extension API a NOP unless the flag is provided.

BUG=303155

TEST=Run ash with the keyboard (--enable-virtual-keyboard) and try to use the swipe selection feature by typing some stuff and swiping across the keyboard area to move the selection. Note that it doesn't work unless you also specify the --enable-swipe-selection feature.

Review URL: https://codereview.chromium.org/35593002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230894 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230893
SVN changes up to revision 230894