Properly handle the case when a parallel download becomes non-parallel

Properly handle the case when a parallel download becomes non-parallel

When finch is used, it is possible that user can resume a previous parallel
download without enabling parallel downloading.
This change handles that case by truncating the file
and discard all the received slices

BUG=644352
Review-Url: https://codereview.chromium.org/2812263004
Cr-Commit-Position: refs/heads/master@{#464538}
Committed: https://chromium.googlesource.com/chromium/src/+/4f3c18cf2a88b9a88f42fc18461522f718685e59

[qinmin, 2017-04-12 22:29:08]

qinmin@chromium.org changed reviewers:
+ xingliu@chromium.org

[qinmin, 2017-04-12 22:29:08]

PTAL

[xingliu, 2017-04-13 17:20:18]

lgtm.

[qinmin, 2017-04-13 17:26:08]

The CQ bit was checked by qinmin@chromium.org

[commit-bot: I haz the power, 2017-04-13 17:26:55]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-13 17:33:53]

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

[commit-bot: I haz the power, 2017-04-13 17:33:55]

Try jobs failed on following builders:
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[qinmin, 2017-04-13 19:55:39]

The CQ bit was checked by qinmin@chromium.org

[qinmin, 2017-04-13 19:55:39]

The patchset sent to the CQ was uploaded after l-g-t-m from xingliu@chromium.org
Link to the patchset: https://codereview.chromium.org/2812263004/#ps20001
(title: "rebase")

[commit-bot: I haz the power, 2017-04-13 19:56:28]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-13 20:50:32]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1492113339135300,
"parent_rev": "da4c490926045f242ff60f729b9a4abc95e3f4ca", "commit_rev":
"4f3c18cf2a88b9a88f42fc18461522f718685e59"}

[commit-bot: I haz the power, 2017-04-13 20:51:25]

Description was changed from

==========
Properly handle the case when a parallel download becomes non-parallel

When finch is used, it is possible that user can resume a previous parallel
download without enabling parallel downloading.
This change handles that case by truncating the file
and discard all the received slices

BUG=644352
==========

to

==========
Properly handle the case when a parallel download becomes non-parallel

When finch is used, it is possible that user can resume a previous parallel
download without enabling parallel downloading.
This change handles that case by truncating the file
and discard all the received slices

BUG=644352

Review-Url: https://codereview.chromium.org/2812263004
Cr-Commit-Position: refs/heads/master@{#464538}
Committed:
https://chromium.googlesource.com/chromium/src/+/4f3c18cf2a88b9a88f42fc184615...
==========

[commit-bot: I haz the power, 2017-04-13 20:51:26]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/4f3c18cf2a88b9a88f42fc184615...