Update scanning to scan files in small batches (well batches of 1)...this fixes an issue where scan…

Update scanning to scan files in small batches (well batches of 1)...this fixes an issue where scanning appeared to be frozen for long periods of time.

This change also sets the stage for making Scans cancelable...which we'll want to do when a user changes directory...and even allow them to explicitly cancel a scan from the details panel.

TEST=MediaScannerTest

TBR=hirono  // for mock_media_scanner.js

Committed: https://crrev.com/5f0cd3385cbd2bbd7114651ed296188fe6a0603d
Cr-Commit-Position: refs/heads/master@{#322099}

[Steve McKay, 2015-03-24 17:43:12]

Update test media scanner test double with new scan methods.

[Steve McKay, 2015-03-24 17:44:20]

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

[Ben Kwa, 2015-03-24 22:39:41]

One comment on what looks to me like a bug.  Otherwise, lgtm.

https://codereview.chromium.org/1038433002/diff/20001/ui/file_manager/file_ma...
File ui/file_manager/file_manager/background/js/media_scanner.js (right):

https://codereview.chromium.org/1038433002/diff/20001/ui/file_manager/file_ma...
ui/file_manager/file_manager/background/js/media_scanner.js:141: var
scanPromises = entries.forEach(this.onUniqueFileFound_.bind(this, scan));
Did you mean entries.map here?

[Steve McKay, 2015-03-24 22:52:02]

Respond to review comments.

[Steve McKay, 2015-03-24 22:52:12]

The CQ bit was checked by smckay@chromium.org

[Steve McKay, 2015-03-24 22:52:12]

The patchset sent to the CQ was uploaded after l-g-t-m from kenobi@chromium.org
Link to the patchset: https://codereview.chromium.org/1038433002/#ps40001
(title: "Respond to review comments.")

[Steve McKay, 2015-03-24 22:52:23]

Dones. Thanks.

https://codereview.chromium.org/1038433002/diff/20001/ui/file_manager/file_ma...
File ui/file_manager/file_manager/background/js/media_scanner.js (right):

https://codereview.chromium.org/1038433002/diff/20001/ui/file_manager/file_ma...
ui/file_manager/file_manager/background/js/media_scanner.js:141: var
scanPromises = entries.forEach(this.onUniqueFileFound_.bind(this, scan));
On 2015/03/24 22:39:41, Ben Kwa wrote:
> Did you mean entries.map here?

Oh, yes. Done. And added a test case for this method.

[commit-bot: I haz the power, 2015-03-24 22:53:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1038433002/40001

[commit-bot: I haz the power, 2015-03-25 00:03:00]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-03-25 00:03:29]

Patchset 3 (id:??) landed as
https://crrev.com/5f0cd3385cbd2bbd7114651ed296188fe6a0603d
Cr-Commit-Position: refs/heads/master@{#322099}