Move platform abstraction to base library

src/libplatform/task-queue.h

 // Copyright 2013 the V8 project 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 V8_LIBPLATFORM_TASK_QUEUE_H_
 #define V8_LIBPLATFORM_TASK_QUEUE_H_
 
 #include <queue>
 
 #include "src/base/macros.h"
-#include "src/platform/mutex.h"
-#include "src/platform/semaphore.h"
+#include "src/base/platform/mutex.h"
+#include "src/base/platform/semaphore.h"
 
 namespace v8 {
 
 class Task;
 
 namespace internal {
 
 class TaskQueue {
  public:
   TaskQueue();
   ~TaskQueue();
 
   // Appends a task to the queue. The queue takes ownership of |task|.
   void Append(Task* task);
 
   // Returns the next task to process. Blocks if no task is available. Returns
   // NULL if the queue is terminated.
   Task* GetNext();
 
   // Terminate the queue.
   void Terminate();
 
  private:
-  Mutex lock_;
-  Semaphore process_queue_semaphore_;
+  base::Mutex lock_;
+  base::Semaphore process_queue_semaphore_;
   std::queue<Task*> task_queue_;
   bool terminated_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueue);
 };
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_LIBPLATFORM_TASK_QUEUE_H_