Revert of Revert "Post loading tasks on the appropriate WebFrameScheduler's queue."

third_party/WebKit/public/platform/WebTaskRunner.h

Index: third_party/WebKit/public/platform/WebTaskRunner.h
diff --git a/third_party/WebKit/public/platform/WebTaskRunner.h b/third_party/WebKit/public/platform/WebTaskRunner.h
index 4369ad949589fefd4217b8656f6daffa59611e98..6d12febc5cacccda929f0202888f522cdabebf7a 100644
--- a/third_party/WebKit/public/platform/WebTaskRunner.h
+++ b/third_party/WebKit/public/platform/WebTaskRunner.h
@@ -28,11 +28,14 @@
 
     // Schedule a task to be run on the the associated WebThread.
     // Takes ownership of |Task|. Can be called from any thread.
-    virtual void postTask(const WebTraceLocation&, Task*) {}
+    virtual void postTask(const WebTraceLocation&, Task*) = 0;
 
     // Schedule a task to be run after |delayMs| on the the associated WebThread.
     // Takes ownership of |Task|. Can be called from any thread.
-    virtual void postDelayedTask(const WebTraceLocation&, Task*, double delayMs) {}
+    virtual void postDelayedTask(const WebTraceLocation&, Task*, double delayMs) = 0;
+
+    // Returns a clone of the WebTaskRunner.
+    virtual WebTaskRunner* clone() = 0;
 
 #ifdef INSIDE_BLINK
     // Helpers for posting bound functions as tasks.