Refactor Windows TaskQueue code to only need a single high res timer.

webrtc/base/task_queue.h

Index: webrtc/base/task_queue.h
diff --git a/webrtc/base/task_queue.h b/webrtc/base/task_queue.h
index 7d0d41437d5fc5bd13c73cd2d2961c4845640037..c5229b1fe25addd14b4fee55259d0b1665c48857 100644
--- a/webrtc/base/task_queue.h
+++ b/webrtc/base/task_queue.h
@@ -13,7 +13,6 @@
 
 #include <list>
 #include <memory>
-#include <unordered_map>
 
 #if defined(WEBRTC_MAC) && !defined(WEBRTC_BUILD_LIBEVENT)
 #include <dispatch/dispatch.h>
@@ -274,12 +273,8 @@ class LOCKABLE TaskQueue {
   dispatch_queue_t queue_;
   QueueContext* const context_;
 #elif defined(WEBRTC_WIN)
-  class MultimediaTimer;
-  typedef std::unordered_map<UINT_PTR, std::unique_ptr<QueuedTask>>
-      DelayedTasks;
+  class ThreadState;
   static void ThreadMain(void* context);
-  static bool ProcessQueuedMessages(DelayedTasks* delayed_tasks,
-                                    std::vector<MultimediaTimer>* timers);
 
   class WorkerThread : public PlatformThread {
    public: