Fix background colour for Cocoa app list on hover

Fix background colour for Cocoa app list on hover

This color changed recently for the toolkit-views app list, but the
Cocoa app list isn't ready for it yet.

The Cocoa-specific kHighlightedColor was only used in
apps_search_results_controller.mm, so move it there. kSelectedColor is
used there but also in apps_grid_view_item.mm. However, the latter users
a composited draw, so it's fine with the transparent background views
uses.

BUG=469051
Committed: https://crrev.com/b98970ffc6ea2c1b6840d6cb00eedcf96d5758f5
Cr-Commit-Position: refs/heads/master@{#321573}

[tapted, 2015-03-20 10:27:43]

tapted@chromium.org changed reviewers:
+ andresantoso@chromium.org

[tapted, 2015-03-20 10:30:10]

Hi Andre, could you take a look at this one? (looking for a PST reviewer so this
can get in the next canary..). Feel free to CQ :)

Thanks!

[Andre, 2015-03-20 15:34:56]

LGTM

[Andre, 2015-03-20 15:35:09]

The CQ bit was checked by andresantoso@chromium.org

[commit-bot: I haz the power, 2015-03-20 15:35:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1023983002/20001

[commit-bot: I haz the power, 2015-03-20 15:51:58]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-20 15:52:57]

Patchset 2 (id:??) landed as
https://crrev.com/b98970ffc6ea2c1b6840d6cb00eedcf96d5758f5
Cr-Commit-Position: refs/heads/master@{#321573}