Do not enqueue a prefetch task when it prefetched to the end of list.

Do not enqueue a prefetch task when it prefetched to the end of list.

Previously, ListThumbnailLoader preloaded images at the top of list when it preloaded to the end of list. However, especially high priority range is at the end of list, the benefit of preloading top images is small.

BUG=438050
TEST=out/Release/browser_tests --gtest_filter=FileManagerJsTest.ListThumbnailLoader

Committed: https://crrev.com/c3912dc65dd774328124e04a8023d3b5dbe27b07
Cr-Commit-Position: refs/heads/master@{#314538}

[yawano, 2015-02-04 08:52:12]

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

[yawano, 2015-02-04 08:52:13]

PTAL. Thank you!

[hirono, 2015-02-04 09:31:15]

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
File ui/file_manager/file_manager/foreground/js/list_thumbnail_loader.js
(right):

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
ui/file_manager/file_manager/foreground/js/list_thumbnail_loader.js:146: *
@return {!Object} If the thumbnail is not in cache, this returns null.
nit: !Object -> Object

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
File
ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
(right):

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js:161:
listThumbnailLoader.setHighPriorityRange(5, 6);
nit: Maybe we would like to remove the line: 
fileListModel.push(directory1, entry1, entry2, entry3, entry4, entry5);
from setUp function and call setHighPriorityRange before add the items to the
list.
Then we can remove resolveGetOneCallback, and can check
Object.keys(getOneCallbacks).length === 1; directly to focus on what we would
like to test exactly here.

[yawano, 2015-02-04 10:26:57]

Thank you for the review! PTAL.

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
File ui/file_manager/file_manager/foreground/js/list_thumbnail_loader.js
(right):

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
ui/file_manager/file_manager/foreground/js/list_thumbnail_loader.js:146: *
@return {!Object} If the thumbnail is not in cache, this returns null.
On 2015/02/04 09:31:15, hirono wrote:
> nit: !Object -> Object

Done.

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
File
ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
(right):

https://codereview.chromium.org/877513003/diff/1/ui/file_manager/file_manager...
ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js:161:
listThumbnailLoader.setHighPriorityRange(5, 6);
On 2015/02/04 09:31:15, hirono wrote:
> nit: Maybe we would like to remove the line: 
> fileListModel.push(directory1, entry1, entry2, entry3, entry4, entry5);
> from setUp function and call setHighPriorityRange before add the items to the
> list.
> Then we can remove resolveGetOneCallback, and can check
> Object.keys(getOneCallbacks).length === 1; directly to focus on what we would
> like to test exactly here.

Done.

[hirono, 2015-02-04 10:32:58]

lgtm, thanks!

[yawano, 2015-02-04 10:37:21]

New patchsets have been uploaded after l-g-t-m from hirono@chromium.org

[yawano, 2015-02-04 10:37:51]

On 2015/02/04 10:32:58, hirono wrote:
> lgtm, thanks!

Thank you!

[yawano, 2015-02-04 10:37:55]

The CQ bit was checked by yawano@chromium.org

[commit-bot: I haz the power, 2015-02-04 10:39:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/877513003/40001

[commit-bot: I haz the power, 2015-02-04 11:15:21]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-04 11:16:07]

Patchset 3 (id:??) landed as
https://crrev.com/c3912dc65dd774328124e04a8023d3b5dbe27b07
Cr-Commit-Position: refs/heads/master@{#314538}