Files.app: Update visual style of progress center.

Files.app: Update visual style of progress center.

- Color the progress bar green.
- Use Material Design's expand icon to open/shrink progress panel.
- Show expand button slightly higher than the progress bar. (Cancel button should stay in the same level as progress bar.)

BUG=402344
TEST=manually checked

Committed: https://crrev.com/871c2e5bba17b4f8d6fb20f6fb4ad1b436ec801e
Cr-Commit-Position: refs/heads/master@{#316577}

[fukino, 2015-02-17 11:23:10]

fukino@chromium.org changed reviewers:
+ hirono@chromium.org

[fukino, 2015-02-17 11:23:10]

Could you take a look? Thanks!

[hirono, 2015-02-17 12:39:39]

lgtm!

[fukino, 2015-02-17 14:32:39]

On 2015/02/17 12:39:39, hirono wrote:
> lgtm!

Thanks!

[fukino, 2015-02-17 14:32:55]

The CQ bit was checked by fukino@chromium.org

[commit-bot: I haz the power, 2015-02-17 14:34:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/931123002/1

[commit-bot: I haz the power, 2015-02-17 14:59:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-17 14:59:44]

Patchset 1 (id:??) landed as
https://crrev.com/871c2e5bba17b4f8d6fb20f6fb4ad1b436ec801e
Cr-Commit-Position: refs/heads/master@{#316577}