ServiceWorker: Fix data race in shutdown sequence

Source/web/WebEmbeddedWorkerImpl.cpp

Index: Source/web/WebEmbeddedWorkerImpl.cpp
diff --git a/Source/web/WebEmbeddedWorkerImpl.cpp b/Source/web/WebEmbeddedWorkerImpl.cpp
index f9cdbfde727cf76e5b46101e44ee129882f6fdd9..9e5b495fac91e146cab5970f207328db747ec6e9 100644
--- a/Source/web/WebEmbeddedWorkerImpl.cpp
+++ b/Source/web/WebEmbeddedWorkerImpl.cpp
@@ -51,6 +51,7 @@
 #include "platform/network/ContentSecurityPolicyParsers.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebURLRequest.h"
+#include "public/platform/WebWaitableEvent.h"
 #include "public/web/WebDevToolsAgent.h"
 #include "public/web/WebServiceWorkerContextClient.h"
 #include "public/web/WebServiceWorkerNetworkProvider.h"
@@ -171,6 +172,11 @@ WebEmbeddedWorkerImpl::WebEmbeddedWorkerImpl(
 
 WebEmbeddedWorkerImpl::~WebEmbeddedWorkerImpl()
 {
+    if (m_workerThread) {
+        m_workerThread->stop();
+        m_workerThread->terminationEvent()->wait();

[haraken, 2014/10/30 02:40:24]

Can we create a helper method like WorkerThread::terminateAndWait() and use it
here?

[Kunihiko Sakamoto, 2014/10/30 04:50:15]

Done.

+    }

[haraken, 2014/10/30 02:40:24]

Don't you need to call m_workerInspectorProxy->workerThreadTerminated() ?

[Kunihiko Sakamoto, 2014/10/30 04:50:15]

No - WebEmbeddedWorkerImpl::terminateWorkerContext() should be called
beforehand.
(For the same reason, m_workerThread->stop() above isn't really needed. I've put
it just in case.)

+
     ASSERT(runningWorkerInstances().contains(this));
     runningWorkerInstances().remove(this);
     ASSERT(m_webView);