Add blink::WebWaitableEvent interface (blink side)

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index b4f463dc9b28e4c498b9ad5896e44dc3f12ce19e..c410735fb80fabb7186f53a7c9136a54ae77bbfb 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -88,13 +88,14 @@ class WebSpeechSynthesizer;
 class WebSpeechSynthesizerClient;
 class WebStorageNamespace;
 class WebStorageQuotaCallbacks;
-class WebUnitTestSupport;
+struct WebFloatPoint;
 class WebThemeEngine;
 class WebThread;
 class WebURL;
 class WebURLLoader;
+class WebUnitTestSupport;
+class WebWaitableEvent;
 class WebWorkerRunLoop;
-struct WebFloatPoint;
 struct WebLocalizedString;
 struct WebSize;
 
@@ -363,6 +364,18 @@ public:
     virtual WebThread* currentThread() { return 0; }
 
 
+    // WaitableEvent -------------------------------------------------------
+
+    // Creates an embedder-defined waitable event object.
+    virtual WebWaitableEvent* createWaitableEvent() { return 0; }
+
+    // Waits on multiple events and returns the event object that has been
+    // signaled. This may return 0 if it fails to wait events.
+    // Any event objects given to this method must not deleted while this
+    // wait is happening.
+    virtual WebWaitableEvent* waitMultipleEvents(const WebVector<WebWaitableEvent*>& events) { return 0; }
+
+
     // Profiling -----------------------------------------------------------
 
     virtual void decrementStatsCounter(const char* name) { }