compositor-worker: Get the thread to run compositor-workers from the Platform.

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index 632fd6dc9a022ea1126060ffeb5c2263223e12d8..5eef23611081358bf77d3ccb5a6d903d6b8f63cc 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -202,7 +202,7 @@ PlatformThreadId WorkerThread::platformThreadId()
 {
     if (!m_started)
         return 0;
-    return backingThread().platformThread().threadId();
+    return backingThread().threadId();
 }
 
 void WorkerThread::initialize(PassOwnPtr<WorkerThreadStartupData> startupData)
@@ -212,7 +212,7 @@ void WorkerThread::initialize(PassOwnPtr<WorkerThreadStartupData> startupData)
     WorkerThreadStartMode startMode = startupData->m_startMode;
     OwnPtr<Vector<char>> cachedMetaData = startupData->m_cachedMetaData.release();
     V8CacheOptions v8CacheOptions = startupData->m_v8CacheOptions;
-    m_webScheduler = backingThread().platformThread().scheduler();
+    m_webScheduler = backingThread().scheduler();
 
     {
         MutexLocker lock(m_threadStateMutex);
@@ -415,21 +415,17 @@ void WorkerThread::postTask(const WebTraceLocation& location, PassOwnPtr<Executi
     backingThread().postTask(location, WorkerThreadTask::create(*this, task, true).leakPtr());
 }
 
-void WorkerThread::postDelayedTask(const WebTraceLocation& location, PassOwnPtr<ExecutionContextTask> task, long long delayMs)
-{
-    backingThread().postDelayedTask(location, WorkerThreadTask::create(*this, task, true).leakPtr(), delayMs);
-}
-
 void WorkerThread::initializeBackingThread()
 {
     ASSERT(isCurrentThread());
-    backingThread().initialize();
+    m_gcSupport = GCSupportForWebThread::create(backingThread());
 }
 
 void WorkerThread::shutdownBackingThread()
 {
     ASSERT(isCurrentThread());
-    backingThread().shutdown();
+    m_webScheduler->shutdown();
+    m_gcSupport.clear();
 }
 
 v8::Isolate* WorkerThread::initializeIsolate()