Fix data race in blink::WorkerMessagingProxy::reportException

Also make it impossible to access WorkerThread::workerGlobalScope
on a wrong thread at least from outside the class

BUG=520012,460445

Review URL: https://codereview.chromium.org/1305453003

git-svn-id: svn://svn.chromium.org/blink/trunk@200821 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/workers/WorkerMessagingProxy.cpp

@@ -56,6 +56,12 @@ namespace blink {
 
 namespace {
 
+void processExceptionOnWorkerGlobalScope(int exceptionId, bool isHandled, ExecutionContext* scriptContext)
+{
+    WorkerGlobalScope* globalScope = toWorkerGlobalScope(scriptContext);
+    globalScope->exceptionHandled(exceptionId, isHandled);
+}
+
 void processMessageOnWorkerGlobalScope(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray> channels, WorkerObjectProxy* workerObjectProxy, ExecutionContext* scriptContext)
 {
     WorkerGlobalScope* globalScope = toWorkerGlobalScope(scriptContext);
@@ -166,8 +172,7 @@ void WorkerMessagingProxy::reportException(const String& errorMessage, int lineN
 
     RefPtrWillBeRawPtr<ErrorEvent> event = ErrorEvent::create(errorMessage, sourceURL, lineNumber, columnNumber, nullptr);
     bool errorHandled = !m_workerObject->dispatchEvent(event);
-
-    postTaskToWorkerGlobalScope(createCrossThreadTask(&WorkerGlobalScope::exceptionHandled, m_workerThread->workerGlobalScope(), exceptionId, errorHandled));
+    postTaskToWorkerGlobalScope(createCrossThreadTask(&processExceptionOnWorkerGlobalScope, exceptionId, errorHandled));
 }
 
 void WorkerMessagingProxy::reportConsoleMessage(MessageSource source, MessageLevel level, const String& message, int lineNumber, const String& sourceURL)

third_party/WebKit/Source/core/workers/WorkerThread.cpp

@@ -321,6 +321,12 @@ void WorkerThread::terminateAndWait()
     m_terminationEvent->wait();
 }
 
+WorkerGlobalScope* WorkerThread::workerGlobalScope()
+{
+    ASSERT(isCurrentThread());
+    return m_workerGlobalScope.get();
+}
+
 bool WorkerThread::terminated()
 {
     MutexLocker lock(m_threadStateMutex);

third_party/WebKit/Source/core/workers/WorkerThread.h

@@ -106,7 +106,8 @@ public:
     void willEnterNestedLoop();
     void didLeaveNestedLoop();
 
-    WorkerGlobalScope* workerGlobalScope() const { return m_workerGlobalScope.get(); }
+    // Can be called only on the worker thread, WorkerGlobalScope is not thread safe.
+    WorkerGlobalScope* workerGlobalScope();
 
     // Returns true once one of the terminate* methods is called.
     bool terminated();