Add EmbeddedWorker interfaces in Blink API

public/web/WebEmbeddedWorker.h

Index: public/web/WebEmbeddedWorker.h
diff --git a/public/web/mac/WebScrollbarTheme.h b/public/web/WebEmbeddedWorker.h
similarity index 64%
copy from public/web/mac/WebScrollbarTheme.h
copy to public/web/WebEmbeddedWorker.h
index 66cff89944e0d58c85f0ac5d4a5e0eb0fc1c1a6e..707ab09968699cb1f4884f715cfc68e9e9a657c4 100644
--- a/public/web/mac/WebScrollbarTheme.h
+++ b/public/web/WebEmbeddedWorker.h
@@ -28,25 +28,35 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebScrollbarTheme_h
-#define WebScrollbarTheme_h
+#ifndef WebEmbeddedWorker_h
+#define WebEmbeddedWorker_h
 
 #include "public/platform/WebCommon.h"
 
 namespace blink {
 
-class WebScrollbarTheme {
+class WebServiceWorkerContextClient;
+struct WebEmbeddedWorkerStartData;
+
+// An interface to start and terminate an embedded worker.
+// All methods of this class must be called on the main thread.
+class WebEmbeddedWorker {
 public:
-    // Updates the scrollbar appearance and behavior.
-    // |initialButtonDelay| is the current value of NSScrollerButtonDelay from NSUserDefaults.
-    // |autoscrollButtonDelay| is the current value of NSScrollerButtonPeriod from NSUserDefaults.
-    // |jumpOnTrackClick| is the current value of AppleScrollerPagingBehavior from NSUserDefaults.
-    // |redraw| is true if the update requires a redraw to include the change.
-    BLINK_EXPORT static void updateScrollbars(
-        float initialButtonDelay, float autoscrollButtonDelay,
-        bool jumpOnTrackClick, bool redraw);
+    // Invoked on the main thread to instantiate a WebEmbeddedWorker.
+    // The given WebWorkerContextClient and WebWorkerPermissionClientProxy are
+    // going to be passed on to the worker thread and is held by a newly
+    // created WorkerGlobalScope.
+    BLINK_EXPORT static WebEmbeddedWorker* create(
+        WebServiceWorkerContextClient*,
+        WebWorkerPermissionClientProxy*);
+
+    virtual ~WebEmbeddedWorker() { }
+
+    // Starts and terminates WorkerThread and WorkerGlobalScope.
+    virtual void startWorkerContext(const WebEmbeddedWorkerStartData&) = 0;
+    virtual void terminateWorkerContext() = 0;
 };
 
 } // namespace blink
 
-#endif
+#endif // WebEmbeddedWorker_h