Update Media Router WebUI Icons.

Update Media Router WebUI Icons.

Some icons are similar but not exactly what we had previously. Added 2X versions of the downward arrow (default and hover) as well as the sad face icon.

BUG=464222
Committed: https://crrev.com/e156661a7dd822a182a805d0d94af00d70984e5a
Cr-Commit-Position: refs/heads/master@{#322814}

[apacible, 2015-03-24 21:06:11]

apacible@chromium.org changed reviewers:
+ jhawkins@google.com, mfoltz@chromium.org

[apacible, 2015-03-24 21:08:43]

PTAL, thanks!

Icons proposed by UX, OK'd by PM. One down arrow icon (showing) will be updated
later; we're currently looking into a couple of alternatives for this.

[mark a. foltz, 2015-03-24 22:54:47]

lgtm

[apacible, 2015-03-25 20:59:15]

ping jhawkins for browser_resources.grd

Down arrow icon (showing) will be updated in a future CL.

[James Hawkins, 2015-03-30 17:00:02]

jhawkins@chromium.org changed reviewers:
+ jhawkins@chromium.org
- jhawkins@google.com

[James Hawkins, 2015-03-30 17:00:35]

lgtm

[apacible, 2015-03-30 17:05:44]

The CQ bit was checked by apacible@chromium.org

[commit-bot: I haz the power, 2015-03-30 17:06:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1033813002/1

[commit-bot: I haz the power, 2015-03-30 18:23:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-30 18:24:12]

Patchset 1 (id:??) landed as
https://crrev.com/e156661a7dd822a182a805d0d94af00d70984e5a
Cr-Commit-Position: refs/heads/master@{#322814}