[3b] Load data via WebDataConsumerHandle in FetchManager::Loader

Load data via WebDataConsumerHandle in FetchManager::Loader

This CL loads data in Fetch API via stream by setting setUseStreamOnResponse().

FetchManager::Loader::Canceller is removed because cancellation from WebDataConsumerHandle is notified via didFail() by https://codereview.chromium.org/1186053004/.

BUG=480746
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197728

[hiroshige, 2015-06-18 05:50:10]

hiroshige@chromium.org changed reviewers:
+ yhirano@chromium.org

[hiroshige, 2015-06-18 05:53:11]

PTAL.

[yhirano, 2015-06-19 06:36:54]

lgtm

[hiroshige, 2015-06-23 10:52:25]

The CQ bit was checked by hiroshige@chromium.org to run a CQ dry run

[hiroshige, 2015-06-23 10:52:26]

The patchset sent to the CQ was uploaded after l-g-t-m from yhirano@chromium.org
Link to the patchset: https://codereview.chromium.org/1178043004/#ps40001
(title: "Rebase.")

[commit-bot: I haz the power, 2015-06-23 10:52:40]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1178043004/40001

[commit-bot: I haz the power, 2015-06-23 12:08:50]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-23 12:08:51]

Dry run: Try jobs failed on following builders:
  mac_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/60268)

[hiroshige, 2015-06-24 09:35:39]

The CQ bit was checked by hiroshige@chromium.org

[commit-bot: I haz the power, 2015-06-24 09:35:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1178043004/40001

[commit-bot: I haz the power, 2015-06-24 10:22:46]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197728