Revert of MSE: Verify MediaLog events created by existing MP4 unit tests

Revert of MSE: Verify MediaLog events created by existing MP4 unit tests (patchset #2 id:20001 of https://codereview.chromium.org/1300013002/ )

Reason for revert:
Prerequisite CL (https://codereview.chromium.org/1300943002/) is breaking windows bots (http://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/41148), so reverting both this and it to unblock tree.

Original issue's description:
> MSE: Verify MediaLog events created by existing MP4 unit tests
>
> Similar to previous changes r342861 and
> https://codereview.chromium.org/1300943002/, this change updates media
> unit tests to provide a StrictMock<MockMediaLog> to verify MediaLog
> events produced with existing MSE MP4 unit tests. While log message
> maintenance burden is increased, helpers are used to reduce that burden
> while gaining improved resilience against logging regression.
>
> This CL does not verify all possible MSE MP4 parser MEDIA_LOGs, just
> those that are emitted by existing unit tests.
>
> TEST=no regression
>
> Committed: https://crrev.com/194a2651ece516dc91fa0da9aa1675afd307e36e
> Cr-Commit-Position: refs/heads/master@{#345183}

TBR=xhwang@chromium.org,chcunningham@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/61053d4768697c51bad15d7a9bdffa98c591bb7e
Cr-Commit-Position: refs/heads/master@{#345205}

[wolenetz, 2015-08-24 23:34:40]

Created Revert of MSE: Verify MediaLog events created by existing MP4 unit tests

[commit-bot: I haz the power, 2015-08-24 23:35:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1306783003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1306783003/1

[commit-bot: I haz the power, 2015-08-24 23:36:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-24 23:37:05]

Patchset 1 (id:??) landed as
https://crrev.com/61053d4768697c51bad15d7a9bdffa98c591bb7e
Cr-Commit-Position: refs/heads/master@{#345205}

[wolenetz, 2015-08-27 02:09:11]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1317063003/ by wolenetz@chromium.org.

The reason for reverting is: Relanding this now that the fixed prerequisite CL
(https://codereview.chromium.org/1306923004/) has landed..