Refactor RtpSender and SSRCDatabase a bit.

webrtc/modules/rtp_rtcp/source/ssrc_database.h

 /*
  *  Copyright (c) 2011 The WebRTC 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 in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_SSRC_DATABASE_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_SSRC_DATABASE_H_
 
 #include <set>
 
+#include "webrtc/base/criticalsection.h"
 #include "webrtc/base/random.h"
 #include "webrtc/base/scoped_ptr.h"
-#include "webrtc/system_wrappers/include/static_instance.h"
+#include "webrtc/base/thread_annotations.h"
+#include "webrtc/base/thread_checker.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
-class CriticalSectionWrapper;
 
 class SSRCDatabase {
  public:
-  static SSRCDatabase* GetSSRCDatabase();
-  static void ReturnSSRCDatabase();
+  SSRCDatabase();
+  ~SSRCDatabase();
 
   uint32_t CreateSSRC();
   void RegisterSSRC(uint32_t ssrc);
   void ReturnSSRC(uint32_t ssrc);
 
- protected:
-  SSRCDatabase();
-  virtual ~SSRCDatabase();
-
-  static SSRCDatabase* CreateInstance() { return new SSRCDatabase(); }
-
  private:
-  // Friend function to allow the SSRC destructor to be accessed from the
-  // template class.
-  friend SSRCDatabase* GetStaticInstance<SSRCDatabase>(
-      CountOperation count_operation);
-
-  rtc::scoped_ptr<CriticalSectionWrapper> crit_;
+  rtc::CriticalSection crit_;
   Random random_ GUARDED_BY(crit_);
   std::set<uint32_t> ssrcs_ GUARDED_BY(crit_);
+  rtc::ThreadChecker thread_checker_;
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_SSRC_DATABASE_H_