Remove WebKit::Platform dependencies from cc

cc/thread.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CCThread_h
 #define CCThread_h
 
+#include "base/callback.h"
 #include "base/basictypes.h"
-#include "base/threading/platform_thread.h"
-#include <wtf/PassOwnPtr.h>
 
 namespace cc {
 
 // Thread provides basic infrastructure for messaging with the compositor in a
 // platform-neutral way.
 class Thread {
 public:
     virtual ~Thread() { }
 
-    class Task {
-    public:
-        virtual ~Task() { }
-        virtual void performTask() = 0;
-        void* instance() const { return m_instance; }
-    protected:
-        Task(void* instance) : m_instance(instance) { }
-        void* m_instance;
-    private:
-        DISALLOW_COPY_AND_ASSIGN(Task);
-    };
-
-    // Executes the task on context's thread asynchronously.
-    virtual void postTask(PassOwnPtr<Task>) = 0;
+    // Executes the callback on context's thread asynchronously.
+    virtual void postTask(base::Closure cb) = 0;
 
     // Executes the task after the specified delay.
-    virtual void postDelayedTask(PassOwnPtr<Task>, long long delayMs) = 0;
+    virtual void postDelayedTask(base::Closure cb, long long delayMs) = 0;
 
-    virtual base::PlatformThreadId threadID() const = 0;
+    virtual bool belongsToCurrentThread() const = 0;
 };
 
 }
 
 #endif