[CacheStorage] Prioritize Size operations over other scheduled operations

[CacheStorage] Prioritize Size operations over other scheduled operations

This CL runs pending Size() operations immediately after backend
initialization instead of in scheduler order. This is because
scheduled operations might depend on the QuotaManager which may call
Size() mid-operation.

BUG=605663
Review URL: https://codereview.chromium.org/1916473002

Cr-Commit-Position: refs/heads/master@{#389184}
(cherry picked from commit 8b14d719f48c5d2b1f2f61fec372ee01e5f938a8)

Committed: https://chromium.googlesource.com/chromium/src/+/e09345bdc7a8dccf7baa38a3959d7ba7380fc54c

[jkarlin, 2016-05-06 19:07:05]

Description was changed from

==========
[CacheStorage] Prioritize Size operations over other scheduled operations

This CL runs pending Size() operations immediately after backend
initialization instead of in scheduler order. This is because
scheduled operations might depend on the QuotaManager which may call
Size() mid-operation.

BUG=605663

Review URL: https://codereview.chromium.org/1916473002

Cr-Commit-Position: refs/heads/master@{#389184}
(cherry picked from commit 8b14d719f48c5d2b1f2f61fec372ee01e5f938a8)
==========

to

==========
[CacheStorage] Prioritize Size operations over other scheduled operations

This CL runs pending Size() operations immediately after backend
initialization instead of in scheduler order. This is because
scheduled operations might depend on the QuotaManager which may call
Size() mid-operation.

BUG=605663

Review URL: https://codereview.chromium.org/1916473002

Cr-Commit-Position: refs/heads/master@{#389184}
(cherry picked from commit 8b14d719f48c5d2b1f2f61fec372ee01e5f938a8)

Committed:
https://chromium.googlesource.com/chromium/src/+/e09345bdc7a8dccf7baa38a3959d...
==========

[jkarlin, 2016-05-06 19:07:07]

Committed patchset #2 (id:20001) manually as
e09345bdc7a8dccf7baa38a3959d7ba7380fc54c.