Files.app: Fix task cancellation.

Files.app: Fix task cancellation.

- Fix the task queue so that cancelling a task doesn't leave it hanging out in the queue, which then will jam everything up.
- Fix the error code so that errors are handled consistently (and are non-terminal, as they should be)
- Rename UpdateType.SUCCESS to UpdateType.COMPLETE.  This better reflects the fact that errors can occur during an import task but the task still runs to completion.

BUG=460597
Committed: https://crrev.com/fb5551a709a997209e1504d0eacc8562c1740f03
Cr-Commit-Position: refs/heads/master@{#317538}

[Ben Kwa, 2015-02-20 22:12:24]

kenobi@chromium.org changed reviewers:
+ mtomasz@chromium.org, smckay@chromium.org

[Steve McKay, 2015-02-20 22:30:02]

LGTM.

Please add a tab column to the backlog where we can track changes that need to
be merged.

Once submitted I believe you'll need to mark it with Merge-Requested && M-42.

[mtomasz, 2015-02-23 00:59:22]

lgtm

https://codereview.chromium.org/947583002/diff/1/ui/file_manager/file_manager...
File ui/file_manager/file_manager/background/js/media_import_handler.js (right):

https://codereview.chromium.org/947583002/diff/1/ui/file_manager/file_manager...
ui/file_manager/file_manager/background/js/media_import_handler.js:124: break;
nit: indent

[Steve McKay, 2015-02-23 03:17:55]

Ben's got a bunch of extra curricular activities next week. I'm gonna this the
commit box on this change, and I'll send you a followup CL (tomorrow) with the
requested fixes.

[Steve McKay, 2015-02-23 03:18:00]

The CQ bit was checked by smckay@chromium.org

[commit-bot: I haz the power, 2015-02-23 03:18:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/947583002/1

[commit-bot: I haz the power, 2015-02-23 03:24:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-23 03:24:59]

Patchset 1 (id:??) landed as
https://crrev.com/fb5551a709a997209e1504d0eacc8562c1740f03
Cr-Commit-Position: refs/heads/master@{#317538}

[Steve McKay, 2015-02-23 18:20:41]

On 2015/02/23 03:24:59, I haz the power (commit-bot) wrote:
> Patchset 1 (id:??) landed as
> https://crrev.com/fb5551a709a997209e1504d0eacc8562c1740f03
> Cr-Commit-Position: refs/heads/master@{#317538}

Submitted TBR as https://codereview.chromium.org/949823005/

[Steve McKay, 2015-02-24 18:15:29]

https://codereview.chromium.org/947583002/diff/1/ui/file_manager/file_manager...
File ui/file_manager/file_manager/background/js/media_import_handler.js (right):

https://codereview.chromium.org/947583002/diff/1/ui/file_manager/file_manager...
ui/file_manager/file_manager/background/js/media_import_handler.js:124: break;
On 2015/02/23 00:59:22, mtomasz wrote:
> nit: indent

Fixed in followup CL.