Adds a CancellableTaskFactory and exposes postLoadingTasks to Blink

public/platform/WebThread.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 21 matching lines @@
 
 // Always an integer value.
 typedef uintptr_t PlatformThreadId;
 
 // Provides an interface to an embedder-defined thread implementation.
 //
 // Deleting the thread blocks until all pending, non-delayed tasks have been
 // run.
 class BLINK_PLATFORM_EXPORT WebThread {
 public:
-    class Task {
+    class BLINK_PLATFORM_EXPORT Task {
     public:
         virtual ~Task() { }
         virtual void run() = 0;
     };
 
     class BLINK_PLATFORM_EXPORT TaskObserver {
     public:
         virtual ~TaskObserver() { }
         virtual void willProcessTask() = 0;
         virtual void didProcessTask() = 0;
@@ skipping 19 matching lines @@
     // exitRunLoop() runs tasks until there are no tasks available to run, then returns control to the caller of enterRunLoop().
     // Must be called when the WebThread is running.
     virtual void exitRunLoop() = 0;
 
     virtual ~WebThread() { }
 };
 
 } // namespace blink
 
 #endif