Omnibox UI Refresh: Make "invisible focus" apperance more consistent

On the New Tab Page, when the user clicks the fake Google search box,
i.e. the "fakebox", we give the Omnibox "invisible focus".

This is a unique state where we set the Omnibox is focused and
capturing key events, but the caret is invisible.

In the past, the caret being invisible was sufficient for the Omnibox
to be "invisibly" focused.

In MD Refresh, however, we have three new focus indicators:
 1. Focus ring
 2. Placeholder text
 3. Background color change

This CL updates all three of the above visual indicators for the
Omnibox to be keyed on the invisible-focus state rather than the
ordinary focus state.

This solves the flicker present in the below bug and actually follows
the concept of invisible-focus correctly.

The concept of invisible-focus is kind of evil, and long term, we would
like to get rid of it -- but this is a short term fix for MD Refresh.

Bug: 859826
Change-Id: I2e0ede93e69485745bbf119a3f366b0dbfa197ab
Reviewed-on: https://chromium-review.googlesource.com/1144211
Commit-Queue: Tommy Li <tommycli@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576752}
6 files changed