[Downloads] BaseFile shouldn't read past the expected EOF for a stub file.

[Downloads] BaseFile shouldn't read past the expected EOF for a stub file.

The partial stub file may have more data than expected due to
discrepancy between persisted metadata and the intermediate file.
Currently we resolve this conflict in favor of persisted metadata and
truncate the partial file to match. In this case, BaseFile::Initialize()
-> BaseFile::CalculatePartialHash() ended up reading past teh expected
EOF for large intermediate files. Consequently, BaseFile would conclude
incorrectly that the partial file is too short.

This patch fixes this bug by correctly stopping reading prior to the
expected EOF.

R=svaldez@chromium.org
BUG=603330
Committed: https://crrev.com/aeeba88e199ca02307bf5dfb651c867cfdb94a16
Cr-Commit-Position: refs/heads/master@{#387370}

[svaldez, 2016-04-14 14:41:30]

lgtm

[asanka, 2016-04-14 14:45:37]

The CQ bit was checked by asanka@chromium.org

[commit-bot: I haz the power, 2016-04-14 14:45:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1887873002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1887873002/1

[asanka, 2016-04-14 15:41:27]

The CQ bit was unchecked by asanka@chromium.org

[asanka, 2016-04-14 17:29:17]

The CQ bit was checked by asanka@chromium.org

[asanka, 2016-04-14 17:29:18]

The patchset sent to the CQ was uploaded after l-g-t-m from svaldez@chromium.org
Link to the patchset: https://codereview.chromium.org/1887873002/#ps20001
(title: " ")

[commit-bot: I haz the power, 2016-04-14 17:29:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1887873002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1887873002/20001

[commit-bot: I haz the power, 2016-04-14 18:17:39]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-04-14 18:19:54]

Description was changed from

==========
[Downloads] BaseFile shouldn't read past the expected EOF for a stub file.

The partial stub file may have more data than expected due to
discrepancy between persisted metadata and the intermediate file.
Currently we resolve this conflict in favor of persisted metadata and
truncate the partial file to match. In this case, BaseFile::Initialize()
-> BaseFile::CalculatePartialHash() ended up reading past teh expected
EOF for large intermediate files. Consequently, BaseFile would conclude
incorrectly that the partial file is too short.

This patch fixes this bug by correctly stopping reading prior to the
expected EOF.

R=svaldez@chromium.org
BUG=603330
==========

to

==========
[Downloads] BaseFile shouldn't read past the expected EOF for a stub file.

The partial stub file may have more data than expected due to
discrepancy between persisted metadata and the intermediate file.
Currently we resolve this conflict in favor of persisted metadata and
truncate the partial file to match. In this case, BaseFile::Initialize()
-> BaseFile::CalculatePartialHash() ended up reading past teh expected
EOF for large intermediate files. Consequently, BaseFile would conclude
incorrectly that the partial file is too short.

This patch fixes this bug by correctly stopping reading prior to the
expected EOF.

R=svaldez@chromium.org
BUG=603330

Committed: https://crrev.com/aeeba88e199ca02307bf5dfb651c867cfdb94a16
Cr-Commit-Position: refs/heads/master@{#387370}
==========

[commit-bot: I haz the power, 2016-04-14 18:19:54]

Patchset 2 (id:??) landed as
https://crrev.com/aeeba88e199ca02307bf5dfb651c867cfdb94a16
Cr-Commit-Position: refs/heads/master@{#387370}