Added ServiceStatus string for State::kDownloaded.

Added ServiceStatus string for State::kDownloaded.

Downloaded was getting string for Updating, string added for Downloaded.

BUG=486006
Committed: https://crrev.com/463d6c43ea5ceb77e8f0fba13970a3ecb5863d98
Cr-Commit-Position: refs/heads/master@{#329125}

[Deepak, 2015-05-08 15:11:51]

deepak.m1@samsung.com changed reviewers:
+ bauerb@chromium.org, cpu@chromium.org

[Deepak, 2015-05-08 15:11:52]

PTAL

[Bernhard Bauer, 2015-05-08 15:16:07]

bauerb@chromium.org changed reviewers:
+ sorin@chromium.org

[Bernhard Bauer, 2015-05-08 15:16:07]

+Sorin

In principle this seems fine to me, but I'd like to let a component updater
OWNER have their say.

[Sorin Jianu, 2015-05-08 16:53:31]

lgtm

Thank you!

[Bernhard Bauer, 2015-05-09 10:56:13]

lgtm

[Deepak, 2015-05-11 02:57:46]

The CQ bit was checked by deepak.m1@samsung.com

[commit-bot: I haz the power, 2015-05-11 03:00:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132823002/1

[commit-bot: I haz the power, 2015-05-11 09:08:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-11 09:10:40]

Patchset 1 (id:??) landed as
https://crrev.com/463d6c43ea5ceb77e8f0fba13970a3ecb5863d98
Cr-Commit-Position: refs/heads/master@{#329125}