Revert of [tracing] Fix, simplify and speed up accounting of TraceEvent memory overhead

Revert of [tracing] Fix, simplify and speed up accounting of TraceEvent memory overhead (patchset #4 id:60001 of https://codereview.chromium.org/1251203003/ )

Reason for revert:
Speculative revert for https://code.google.com/p/chromium/issues/detail?id=516056

Original issue's description:
> [tracing] Fix, simplify and speed up accounting of TraceEvent memory overhead
>
> So far the accounting of TraceEvent memory overhead worked as follows:
>  - Each TraceEvent keeps a cache of its own overhead.
>  - The TraceBufferChunk (which is approx an array of 64 TraceEvent)
>    keeps a cache of the all 64 TraceEvent, but only when completelly
>    filled.
>
> This is sub-optimal because:
>  - There can be many TraceEvent(s), 10k-100k in a bulky 30s trace:
>    when memory-infra is enabled, this causes a cost of several MB to
>    keep the aforementioned per-TraceEvent caches.
>  - Every time we have to estimate the size of a non-completely-full
>    TraceBufferChunk, we still have to loop over their individual caches.
>  - Least but not last, turns out that the current accounting is just
>    wrong, as we ended up counting the sizeof(TraceEvent) both in
>    TraceBufferChunk and in the individual TraceEvent.
>
> This CL improves the situation as follows:
>  - The per-TraceEvent cache is dropped. Much less memory is used.
>  - The TraceBufferChunk still keeps a cache, but its cache is used in a
>    smarter way and not just when it is full. We simply remember how many
>    TraceEvent(s) we estimated in the previous pass and then estimate just
>    the missing ones.
>  - The double accounting issue is fixed, as now we count TraceEvent(s)
>    only in TraceBufferChunk.
>
> BUG=512383
>
> Committed: https://crrev.com/b2ae97fb331cbad132a8e1aad9a25441fde75048
> Cr-Commit-Position: refs/heads/master@{#340005}

TBR=dsinclair@chromium.org,primiano@chromium.org
BUG=512383
Committed: https://crrev.com/8f329fc15f5fa64f64308244266a304c122a2868
Cr-Commit-Position: refs/heads/master@{#341910}

[oystein (OOO til 10th of July), 2015-08-04 20:16:13]

Created Revert of [tracing] Fix, simplify and speed up accounting of TraceEvent
memory overhead

[oystein (OOO til 10th of July), 2015-08-04 20:17:43]

oysteine@chromium.org changed reviewers:
+ dyen@chromium.org

[David Yen, 2015-08-04 23:17:46]

Looks like this fixed the flakiness, lets get this in and monitor the trybots
more. LGTM (although I'm no owner).

[oystein (OOO til 10th of July), 2015-08-04 23:18:41]

The CQ bit was checked by oysteine@chromium.org

[commit-bot: I haz the power, 2015-08-04 23:19:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1258903003/110001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1258903003/110001

[commit-bot: I haz the power, 2015-08-05 00:39:30]

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

[commit-bot: I haz the power, 2015-08-05 00:39:31]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[oystein (OOO til 10th of July), 2015-08-05 16:05:26]

The CQ bit was checked by oysteine@chromium.org

[commit-bot: I haz the power, 2015-08-05 16:05:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1258903003/110001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1258903003/110001

[commit-bot: I haz the power, 2015-08-05 16:11:03]

Committed patchset #2 (id:110001)

[commit-bot: I haz the power, 2015-08-05 16:12:03]

Patchset 2 (id:??) landed as
https://crrev.com/8f329fc15f5fa64f64308244266a304c122a2868
Cr-Commit-Position: refs/heads/master@{#341910}

[oystein (OOO til 10th of July), 2015-08-06 18:39:36]

A revert of this CL (patchset #2 id:110001) has been created in
https://codereview.chromium.org/1265393007/ by oysteine@chromium.org.

The reason for reverting is: Reverting did not solve crbug.com/516056.