CL: https://codereview.chromium.org/2268933002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0aeb592d32403fe36924953d37b6a0626a0f7e09

commit 0aeb592d32403fe36924953d37b6a0626a0f7e09
Author: nhiroki <nhiroki@chromium.org>
Date: Tue Aug 23 08:18:37 2016

ServiceWorker: Detect forcible worker thread termination in a correct way

WorkerThread::terminated() is not a correct way to detect forcible worker thread
termination during an event dispatch because it just represents that the worker
thread is requested to terminate on the main thread, and it can return true
even if a dispatched event is successfully finished without an interruption.

BUG= 639153 ,  640078 

Review-Url: https://codereview.chromium.org/2268933002
Cr-Commit-Position: refs/heads/master@{#413692}

[modify] https://crrev.com/0aeb592d32403fe36924953d37b6a0626a0f7e09/third_party/WebKit/Source/core/workers/WorkerThread.cpp
[modify] https://crrev.com/0aeb592d32403fe36924953d37b6a0626a0f7e09/third_party/WebKit/Source/core/workers/WorkerThread.h
[modify] https://crrev.com/0aeb592d32403fe36924953d37b6a0626a0f7e09/third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerGlobalScope.cpp