Revert of media-internals: Simplify the code path for creating a media log entry

Revert of media-internals: Simplify the code path for creating a media log entry (patchset #3 id:40001 of https://codereview.chromium.org/1047313002/)

Reason for revert:
http://build.chromium.org/p/chromium.webkit/builders/Mac%20Builder%20%28dbg%29/builds/78706/steps/compile/logs/stdio

Original issue's description:
> media-internals: Simplify the code path for creating a media log entry
>
> Changes MediaLog::CreateLogEvent() to instead be a helper AddLogEvent() that
> both creates and adds the event, and has signature and utility matching LogCB.
> This means various media code pieces no longer must have their own LogCB
> implementations that CreateLogEvent()+AddEvent().
>
> BUG=471902, 260005
> TEST=no media_unittest, layout, or chrome://media-internals log regression observed
>
> Committed: https://crrev.com/aafe49fe9061c489906351db41c318473d1951af
> Cr-Commit-Position: refs/heads/master@{#323149}

TBR=dalecurtis@chromium.org,wolenetz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=471902, 260005
Committed: https://crrev.com/16cd9613c88278d5429d6ba4394e48a516cc889a
Cr-Commit-Position: refs/heads/master@{#323155}

[jianli, 2015-04-01 00:34:38]

Created Revert of media-internals: Simplify the code path for creating a media
log entry

[commit-bot: I haz the power, 2015-04-01 00:35:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1049393002/1

[commit-bot: I haz the power, 2015-04-01 00:35:44]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-01 00:36:38]

Patchset 1 (id:??) landed as
https://crrev.com/16cd9613c88278d5429d6ba4394e48a516cc889a
Cr-Commit-Position: refs/heads/master@{#323155}

[raymes, 2015-04-01 00:45:51]

I've filed https://code.google.com/p/chromium/issues/detail?id=471952