Refactor TimeBase to post tasks. Workers to use real Idle tasks.

Source/core/workers/WorkerThread.h

Index: Source/core/workers/WorkerThread.h
diff --git a/Source/core/workers/WorkerThread.h b/Source/core/workers/WorkerThread.h
index 4a66960a7817ce0179f3d486e3edebeab2ac84a6..1b9be7f651aa04cbd060509dd1b061373c381d92 100644
--- a/Source/core/workers/WorkerThread.h
+++ b/Source/core/workers/WorkerThread.h
@@ -47,7 +47,6 @@ class WebWaitableEvent;
 class WorkerGlobalScope;
 class WorkerInspectorController;
 class WorkerReportingProxy;
-class WorkerSharedTimer;
 class WorkerThreadShutdownFinishTask;
 class WorkerThreadStartupData;
 class WorkerThreadTask;
@@ -122,8 +121,16 @@ protected:
     virtual void destroyIsolate();
     virtual void terminateV8Execution();
 
+    // This is protected virtual for testing.
+    virtual bool doIdleGc(double deadlineSeconds);
+
+    WebThreadSupportingGC* threadForTesting() const
+    {
+        return m_thread.get();
+    }
+
 private:
-    friend class WorkerSharedTimer;
+    friend class WorkerThreadIdleTask;
     friend class WorkerThreadShutdownFinishTask;
 
     void stopInShutdownSequence();
@@ -131,7 +138,7 @@ private:
 
     void initialize();
     void cleanup();
-    void idleHandler();
+    void idleTask(double deadlineSeconds);
     void postDelayedTask(PassOwnPtr<ExecutionContextTask>, long long delayMs);
     void postDelayedTask(const WebTraceLocation&, PassOwnPtr<ExecutionContextTask>, long long delayMs);