MSE: Refine WebM parser unit test MediaLog verification

MSE: Refine WebM parser unit test MediaLog verification

For the approx. 1500 combinations of Opus configurations involved in
each of a couple WebMClusterParserTests, verifies expected MediaLog
sequence for each, rather than just that the set of all logs matches the
union of all expectations. Does this without regressing the tests'
execution time, and allows early detection of failure to prevent test
regression from building tremendous amount of failed expectations state.
Similar state growth, though for otherwise passing tests, is suspected
of causing test crashes on win7 dbg bots in original
http://crrev.com/1300943002#ps40001.

R=xhwang@chromium.org,chcunningham@chromium.org
BUG=524597
TEST=WebMClusterParserTests:
ReadOpusDurationsSimpleBlockAtEndOfCluster, and
PreferOpusDurationsOverBlockDurations

Committed: https://crrev.com/ba46024c5f48ffffaaea0e7d7c4a75a0ac6c5ae1
Cr-Commit-Position: refs/heads/master@{#345764}

[wolenetz, 2015-08-26 00:37:25]

Landing this will first depend on the prereq CL landing and not causing win7 dbg
test bot issue.
Please take a look. Thanks!

[xhwang, 2015-08-26 17:27:57]

lgtm

[chcunningham, 2015-08-26 17:35:29]

lgtm

[wolenetz, 2015-08-26 17:51:27]

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

[commit-bot: I haz the power, 2015-08-26 17:52:35]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1316013002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1316013002/1

[wolenetz, 2015-08-26 17:54:24]

The CQ bit was unchecked by wolenetz@chromium.org

[wolenetz, 2015-08-26 17:56:41]

Thanks for reviews. Prereq CL is pending tree opening so I can watch it more
closely when it lands. I've also started a win_chromium_dbg_ng trybot run to
this CL just now. Current bot runs might fail for unrelated reason (GCS issue
that's causing tree closure).

[wolenetz, 2015-08-26 20:31:42]

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

[commit-bot: I haz the power, 2015-08-26 20:32:25]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1316013002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1316013002/1

[commit-bot: I haz the power, 2015-08-26 21:07:41]

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

[commit-bot: I haz the power, 2015-08-26 21:07:42]

Dry run: This issue passed the CQ dry run.

[wolenetz, 2015-08-27 01:49:20]

The CQ bit was checked by wolenetz@chromium.org

[commit-bot: I haz the power, 2015-08-27 01:49:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1316013002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1316013002/1

[commit-bot: I haz the power, 2015-08-27 01:55:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-27 01:55:57]

Patchset 1 (id:??) landed as
https://crrev.com/ba46024c5f48ffffaaea0e7d7c4a75a0ac6c5ae1
Cr-Commit-Position: refs/heads/master@{#345764}