Revert of Implement timers by posting delayed tasks

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index 5bfc79e165da0239810427ef5f639ddd6b9f174b..02cbc71107f78b6fceeab9788f2b66dd8c348116 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -427,6 +427,12 @@
 
     // WebKit clients must implement this funcion if they use cryptographic randomness.
     virtual void cryptographicallyRandomValues(unsigned char* buffer, size_t length) = 0;
+
+    // Delayed work is driven by a shared timer.
+    typedef void (*SharedTimerFunction)();
+    virtual void setSharedTimerFiredFunction(SharedTimerFunction timerFunction) { }
+    virtual void setSharedTimerFireInterval(double) { }
+    virtual void stopSharedTimer() { }
 
     // Returns an interface to the main thread. Can be null if blink was initialized on a thread without a message loop.
     BLINK_PLATFORM_EXPORT WebThread* mainThread() const;