Use Roboto font family for Media Router WebUI.

Use Roboto font family for Media Router WebUI.

Roboto is the standard typeface for material design. Changes per offline discussion with UX.

BUG=501452
Committed: https://crrev.com/c4222fae98c2c891a7206df770b29370f150af8a
Cr-Commit-Position: refs/heads/master@{#338946}

[apacible, 2015-07-15 04:04:28]

apacible@chromium.org changed reviewers:
+ kmarshall@chromium.org

[apacible, 2015-07-15 04:15:59]

PTAL, thanks!

Screenshots:
- Sink Picker: https://screenshot.googleplex.com/XTLxZHx2nEp.png
- Sink Picker (scrolled down/active):
https://screenshot.googleplex.com/9FJKwbs0J14.png
- Route Details: https://screenshot.googleplex.com/2fsaWqCtWPf.png
- Cast Mode: https://screenshot.googleplex.com/xudBHY3xk4Y.png

Some text is a bit tight with this change. I'm discussing with UX after this
lands.

Examples:
- Having the default font-size (and not 0.75) makes the text bloated:
https://screenshot.googleplex.com/s3dPptfbvrn.png
- Route Details (see above) media details is harder to read. (Content also WIP.)
- Usage of Roboto/Noto/sans-serif font stack per design guidelines versus just
Roboto.

[Kevin M, 2015-07-15 20:12:54]

lgtm

[apacible, 2015-07-15 23:00:46]

Patchset #2 (id:20001) has been deleted

[apacible, 2015-07-15 23:00:49]

The CQ bit was checked by apacible@chromium.org

[commit-bot: I haz the power, 2015-07-15 23:01:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1231173004/1

[commit-bot: I haz the power, 2015-07-15 23:32:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-15 23:33:22]

Patchset 1 (id:??) landed as
https://crrev.com/c4222fae98c2c891a7206df770b29370f150af8a
Cr-Commit-Position: refs/heads/master@{#338946}