[chromedriver] Reuse forwarded adb ports.

chrome/test/chromedriver/net/port_server.h

 // Copyright (c) 2013 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 CHROME_TEST_CHROMEDRIVER_NET_PORT_SERVER_H_
 #define CHROME_TEST_CHROMEDRIVER_NET_PORT_SERVER_H_
 
 #include <list>
 #include <set>
 #include <string>
@@ skipping 36 matching lines @@
   std::list<int> free_;
 };
 
 // Manages reservation of a block of local ports.
 class PortManager {
  public:
   PortManager(int min_port, int max_port);
   ~PortManager();
 
   Status ReservePort(int* port, scoped_ptr<PortReservation>* reservation);
+  // Since we cannot remove forwarded adb ports on older SDKs,
+  // maintain a pool of forwarded ports for reuse.
+  Status ReservePortFromPool(int* port,
+                             scoped_ptr<PortReservation>* reservation);
 
  private:
+  int FindAvailablePort() const;
   void ReleasePort(int port);
+  void ReleasePortToPool(int port);
 
-  base::Lock taken_lock_;
+  base::Lock lock_;
   std::set<int> taken_;
-
+  std::list<int> unused_forwarded_port_;
   int min_port_;
   int max_port_;
 };
 
 #endif  // CHROME_TEST_CHROMEDRIVER_NET_PORT_SERVER_H_