Reland: Create hard links in file migration if necessary.

Reland: Create hard links in file migration if necessary.

TBR=hashimoto@chromium.org

Original CL:
Create hard links in file migration if necessary.

BUG=533750
TEST=unit_tests:FileCacheTest.MigrateCacheFiles

Committed: https://crrev.com/c5c297d58dc4d90423ed222f5bc7c06a84156324
Cr-Commit-Position: refs/heads/master@{#375836}

patch from issue 1698793003 at patchset 20001 (http://crrev.com/1698793003#ps20001)

Committed: https://crrev.com/cbe6dc8d336bcf5e8a9b0e7da7d5b0939bda32e6
Cr-Commit-Position: refs/heads/master@{#381888}

[yawano, 2016-03-18 03:27:42]

The CQ bit was checked by yawano@chromium.org

[commit-bot: I haz the power, 2016-03-18 03:27:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1811933004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1811933004/1

[commit-bot: I haz the power, 2016-03-18 04:53:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-18 04:56:20]

Description was changed from

==========
Reland: Create hard links in file migration if necessary.

TBR=hashimoto@chromium.org

Original CL:
Create hard links in file migration if necessary.

BUG=533750
TEST=unit_tests:FileCacheTest.MigrateCacheFiles

Committed: https://crrev.com/c5c297d58dc4d90423ed222f5bc7c06a84156324
Cr-Commit-Position: refs/heads/master@{#375836}

patch from issue 1698793003 at patchset 20001
(http://crrev.com/1698793003#ps20001)
==========

to

==========
Reland: Create hard links in file migration if necessary.

TBR=hashimoto@chromium.org

Original CL:
Create hard links in file migration if necessary.

BUG=533750
TEST=unit_tests:FileCacheTest.MigrateCacheFiles

Committed: https://crrev.com/c5c297d58dc4d90423ed222f5bc7c06a84156324
Cr-Commit-Position: refs/heads/master@{#375836}

patch from issue 1698793003 at patchset 20001
(http://crrev.com/1698793003#ps20001)

Committed: https://crrev.com/cbe6dc8d336bcf5e8a9b0e7da7d5b0939bda32e6
Cr-Commit-Position: refs/heads/master@{#381888}
==========

[commit-bot: I haz the power, 2016-03-18 04:56:21]

Patchset 1 (id:??) landed as
https://crrev.com/cbe6dc8d336bcf5e8a9b0e7da7d5b0939bda32e6
Cr-Commit-Position: refs/heads/master@{#381888}

[yawano, 2016-03-18 06:13:35]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1815053003/ by yawano@chromium.org.

The reason for reverting is: This CL broke buildbot.
https://build.chromium.org/p/chromium/builders/Win/builds/41435.