Fix security icon colors on light themes

Security icon colors on Chrome for Android and Chrome Custom Tabs should
be as follows:

1. Default toolbar color => green lock/red triangle
2. Dark toolbar color => white icons
3. Light toolbar color with opaque omnibox => green/red
4. Other toolbar color with transparent omnibox => dark icons

BUG=633736
TEST=On Chrome for Android, visit the following URLs and observe the
given security icon colors:
1. https://google.com => green lock
2. https://yahoo.com => white lock
3. https://just-skyline-137219.appspot.com/lightblue => opaque omnibox
with green lock
4. https://garron.net/test/theme-color/?color=%2300ffff => transparent
omnibox with dark lock
In a CCT client app, set the toolbar color to the following colors and then visit https://www.google.com:
1. Default => green lock
2. #ef6c00 => white lock
3. #ffffcc => dark lock
4. #66ffff => dark lock

Review-Url: https://codereview.chromium.org/2274973004
Cr-Commit-Position: refs/heads/master@{#414897}
(cherry picked from commit cf4299907423c27d40182d17099d54a2e97e154c)

Review URL: https://codereview.chromium.org/2290953002 .

Cr-Commit-Position: refs/branch-heads/2785@{#786}
Cr-Branched-From: 68623971be0cfc492a2cb0427d7f478e7b214c24-refs/heads/master@{#403382}
2 files changed