Rename workerGlobalScopeDestroyed to workerThreadTerminated

Rename workerGlobalScopeDestroyed to workerThreadTerminated

This is a follow-up fix for https://codereview.chromium.org/462423003/.
It's inconsistent that workerGlobalScopeDestroyed is called while
workerGlobalScopeStarted is not called. In fact, workerGlobalScopeDestroyed
is a signal to let the WorkerMessagingProxy know that the worker thread
is terminated, it should be renamed to workerThreadTerminated.

BUG=403179
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180254

[haraken, 2014-08-13 12:59:15]

PTAL

[horo, 2014-08-14 01:25:58]

lgtm

[haraken, 2014-08-14 01:28:07]

The CQ bit was checked by haraken@chromium.org

[haraken, 2014-08-14 01:28:14]

Thanks!

[commit-bot: I haz the power, 2014-08-14 01:28:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/haraken@chromium.org/468883002/1

[commit-bot: I haz the power, 2014-08-14 05:27:44]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  blink_presubmit on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/blink_presubmit/builds/1...)

[commit-bot: I haz the power, 2014-08-14 06:32:12]

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

[commit-bot: I haz the power, 2014-08-14 06:32:13]

Try jobs failed on following builders:
  blink_presubmit on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/blink_presubmit/builds/1...)

[jochen (gone - plz use gerrit), 2014-08-14 11:05:42]

lgtm

[haraken, 2014-08-14 11:07:16]

The CQ bit was checked by haraken@chromium.org

[haraken, 2014-08-14 11:07:23]

On 2014/08/14 11:05:42, jochen (slow - soon OOO) wrote:
> lgtm

Thanks!

[commit-bot: I haz the power, 2014-08-14 11:07:47]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/haraken@chromium.org/468883002/1

[commit-bot: I haz the power, 2014-08-14 12:51:55]

Committed patchset #1 (1) as 180254