Adds a separator between custom tab bar and title, based on UX feedback.

Previously, a similar separator was drawn. However, this separator
was always shown (when the theme color was white-ish), and the desired
behavior is to *only* render the separator when the custom tab bar
is visible AND the custom tab bar is white-ish.

This CL will cause a 15% black separator to be drawn at the top of the
custom tab bar, blended with the apps theme color, so it looks like
the separator is drawn onto the title bar.

Bug: 918788
Change-Id: Iba020fe4f059558fe355d18236d5226d35f3a2aa
Reviewed-on: https://chromium-review.googlesource.com/c/1414535
Commit-Queue: Jay Harris <harrisjay@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624514}
2 files changed