Remove the concept of a cleanup task

Remove the concept of a cleanup task

The only cleanup task in Blink which is not internal to a worker thread is
the task to close a WebSQL database. Because 1) only worker threads
support the concept of a cleanup task, and 2) WebSQL isn't supported on
worker threads anymore after https://codereview.chromium.org/561093003/,
we can safely remove the logic to handle cleanup tasks on worker
threads.

BUG=463143
TBR=haraken@chromium.org,jochen@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=195345

[Sami, 2015-05-14 10:13:46]

skyostil@chromium.org changed reviewers:
+ jochen@chromium.org, kinuko@chromium.org

[Sami, 2015-05-14 10:14:17]

This is a reland of https://codereview.chromium.org/1111693003. See
https://codereview.chromium.org/1111693003/#msg42. PTAL.

[kinuko, 2015-05-14 11:27:40]

lgtm

https://codereview.chromium.org/1127123010/diff/20001/Source/core/workers/Wor...
File Source/core/workers/WorkerThread.cpp (right):

https://codereview.chromium.org/1127123010/diff/20001/Source/core/workers/Wor...
Source/core/workers/WorkerThread.cpp:442: if (!m_workerGlobalScope)
Um... it's not really related to this patch, but if terminateAndWait() is called
immediately after start() (and before initialize runs) we don't post shutdown
task, therefore we won't signal m_terminationEvent and terminateAndWait() never
ends.  It seems problematic?  Should we signal m_terminationEvent here?

[Sami, 2015-05-14 11:31:42]

skyostil@chromium.org changed reviewers:
+ haraken@chromium.org

[Sami, 2015-05-14 11:32:17]

Thanks for the quick review!

TBR'in haraken@ and jochen@ since those parts didn't change from last time.

https://codereview.chromium.org/1127123010/diff/20001/Source/core/workers/Wor...
File Source/core/workers/WorkerThread.cpp (right):

https://codereview.chromium.org/1127123010/diff/20001/Source/core/workers/Wor...
Source/core/workers/WorkerThread.cpp:442: if (!m_workerGlobalScope)
On 2015/05/14 11:27:40, kinuko wrote:
> Um... it's not really related to this patch, but if terminateAndWait() is
called
> immediately after start() (and before initialize runs) we don't post shutdown
> task, therefore we won't signal m_terminationEvent and terminateAndWait()
never
> ends.  It seems problematic?  Should we signal m_terminationEvent here?

Yes, I believe that would lead to a deadlock. Let me put together another patch
to add the signaling here.

[Sami, 2015-05-14 11:32:51]

The CQ bit was checked by skyostil@chromium.org

[commit-bot: I haz the power, 2015-05-14 11:33:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1127123010/20001

[commit-bot: I haz the power, 2015-05-14 11:36:08]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=195345

[haraken, 2015-05-14 11:56:34]

LGTM