This implements APIs plumbing theme color changes to java
 side and cached it in web_contents_impl. Fixes the reset
and publish mechanism where we now wait for the first
visually non empty paint to publish the color, making sure
we can reset it on page load begin and have time enough to
get the color update. Once this is in, we can remove the
workarounds on the java side for the reset.

BUG=435768

Review URL: https://codereview.chromium.org/975293004

Cr-Commit-Position: refs/heads/master@{#319377}
7 files changed