[chrome:omnibox] Support zero suggest results.

This CL wires in the current_page and from_omnibox_focus autocomplete input
fields to the UI. Adding these fields allows the debug page to work with the
zero suggest provider, but they also affect other providers, such as search
provider.

Adds 'zero suggest' checkbox which controls the from_omnibox_focus autocomplete
input field. This field enables the zero suggest and clipboard providers while
also disabling the bookmarks, built in, history, history url, keyword, search,
and shortcut providers.

Also adds a 'current url' input box which controls the current_url autocomplete
input field. This field is essential for the zero suggest provider but may also
affect the search and clipboard providers.

To avoid redundant typing, when 'zero suggest' is checked, the 'current url'
input becomes disabled and auto-populated with the contents of the 'omnibox
text' input.

Lastly, changed the accesskey of 'current page context' from 'u' to 'o' in order
to use the accesskey 'u' for the 'current url' input.

Bug: 891303
Change-Id: I51f4815d9f837245b6b6fab03dcec5d009783b6b
Reviewed-on: https://chromium-review.googlesource.com/c/1378246
Reviewed-by: Orin Jaworski <orinj@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618624}
6 files changed