Fix cast from video player by using DriveApiUrlGenerator to generate URL

Fix cast from video player by using DriveApiUrlGenerator to generate URL

This patch fixes the regression which is caused by the following CL.
https://chromium.googlesource.com/chromium/src/+/3315eb5fe7bcb9300995dae3326de2d2c5f3c44a

Since the Styx URLs are updated in that CL, we need to use DriveApiUrlGenerator::GenerateDownloadFileURL to create a download URL to pass a cast device.

BUG=477733
TEST=can cast a video

Committed: https://crrev.com/0dc4cf80cfd2d8976b66f7a9ff79c290c81897e9
Cr-Commit-Position: refs/heads/master@{#326999}

[yoshiki, 2015-04-24 18:08:16]

yoshiki@chromium.org changed reviewers:
+ mtomasz@chromium.org

[yoshiki, 2015-04-24 18:10:07]

@mtomasz: PTAL. Thanks.

[yoshiki, 2015-04-27 04:17:32]

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

[yoshiki, 2015-04-27 04:17:32]

@hirono-san, PTAL at the patch on behalf of Tomasz?

[hirono, 2015-04-27 04:20:37]

lgtm!

[yoshiki, 2015-04-27 04:21:31]

Thank you for quick review!

[yoshiki, 2015-04-27 04:21:34]

The CQ bit was checked by yoshiki@chromium.org

[commit-bot: I haz the power, 2015-04-27 04:21:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1055403004/1

[commit-bot: I haz the power, 2015-04-27 04:59:12]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-27 05:00:04]

Patchset 1 (id:??) landed as
https://crrev.com/0dc4cf80cfd2d8976b66f7a9ff79c290c81897e9
Cr-Commit-Position: refs/heads/master@{#326999}