Create a QUIC wrapper around a mutex and a mutex lock.

net/tools/quic/test_tools/server_thread.h

Index: net/tools/quic/test_tools/server_thread.h
diff --git a/net/tools/quic/test_tools/server_thread.h b/net/tools/quic/test_tools/server_thread.h
index 52cc24b8375b126a201c798e1265a0ac85df5c96..77f00736abbb1eab8408318e0d3984e8463864e2 100644
--- a/net/tools/quic/test_tools/server_thread.h
+++ b/net/tools/quic/test_tools/server_thread.h
@@ -8,9 +8,9 @@
 #include <memory>
 
 #include "base/macros.h"
-#include "base/synchronization/lock.h"
 #include "base/threading/simple_thread.h"
 #include "net/quic/core/quic_config.h"
+#include "net/quic/platform/api/quic_mutex.h"
 #include "net/quic/platform/api/quic_socket_address.h"
 #include "net/tools/quic/quic_server.h"
 
@@ -75,8 +75,9 @@ class ServerThread : public base::SimpleThread {
 
   bool initialized_;
 
-  base::Lock scheduled_actions_lock_;
-  std::deque<std::function<void()>> scheduled_actions_;
+  QuicMutex scheduled_actions_lock_;
+  std::deque<std::function<void()>> scheduled_actions_
+      GUARDED_BY(scheduled_actions_lock_);
 
   DISALLOW_COPY_AND_ASSIGN(ServerThread);
 };