Revert of Run task queue manager work in batches

Revert of Run task queue manager work in batches (patchset #9 id:160001 of https://codereview.chromium.org/845543004/)

Reason for revert:
Trying to see if this is the cause of MediaTest.Yuv* failures on Mac:

http://build.chromium.org/p/chromium.mac/builders/Mac10.9%20Tests/builds/2373
http://build.chromium.org/p/chromium.mac/builders/Mac10.6%20Tests/builds/3274

Original issue's description:
> Run task queue manager work in batches
>
> This patch lets the task queue manager run more than one posted task
> per invocation. This helps reduce the overhead of yielding to and from
> the main message loop and can speed up cases where tasks are posted
> very frequently. One example is indexeddb, where some operations such as
> index building can result in 2500 posted tasks/s (Nexus 7).
>
> This patch also adds accounting for the desired run time of the next
> pending delayed task. This information is used to break out of a work
> batch if a delayed task should be run instead. Doing this avoids adding
> extra delay to delayed tasks.
>
> A potential downside of this change is that it can penalize work that
> runs on the message loop without going through the task queue manager.
> Based on performance tests[1], almost all tasks on the renderer main
> thread are already getting executed by the task queue manager, so I
> believe this change shouldn't cause a regression.
>
> [1] https://docs.google.com/a/chromium.org/spreadsheets/d/1IJZpBabW1pr4fb2T8BlkleHcOvHYrjvmCx_dLesxfMA/edit#gid=1492760051
>
> BUG=444764
>
> Committed: https://crrev.com/d9684457b5349dfc1cc19e8a2d98a69ba00ed058
> Cr-Commit-Position: refs/heads/master@{#312839}

TBR=rmcilroy@chromium.org,alexclarke@chromium.org,picksi@chromium.org,skyostil@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=444764
Committed: https://crrev.com/4ac0f5d78c094e3cdca9f245f999ca37f4eff917
Cr-Commit-Position: refs/heads/master@{#312888}

[jam, 2015-01-23 19:00:01]

Created Revert of Run task queue manager work in batches

[commit-bot: I haz the power, 2015-01-23 19:01:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/867353002/1

[commit-bot: I haz the power, 2015-01-23 19:02:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-23 19:03:47]

Patchset 1 (id:??) landed as
https://crrev.com/4ac0f5d78c094e3cdca9f245f999ca37f4eff917
Cr-Commit-Position: refs/heads/master@{#312888}