cashew: reset local counter on plan transition

src/byte_counter.h

 // Copyright (c) 2010 The Chromium OS 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 SRC_BYTE_COUNTER_H_
 #define SRC_BYTE_COUNTER_H_
 
 #include <string>
 
 #include <base/basictypes.h>  // NOLINT
 
 namespace cashew {
 
 class ByteCounterDelegate;
 
 // interface for byte counter
 class ByteCounter {
   public:
     virtual ~ByteCounter() {}
 
     // to what interface is this counter attached?
     virtual const std::string& GetInterface() const = 0;
 
     // received bytes
     virtual uint64 GetRxBytes() const = 0;
+    virtual void SetRxBytes(uint64 rx_bytes) = 0;
 
     // transmitted bytes
     virtual uint64 GetTxBytes() const = 0;
+    virtual void SetTxBytes(uint64 tx_bytes) = 0;
 
     // set delegate interface that will receive counter updates
     // it's ok to clear this by setting it to NULL
     virtual void SetDelegate(ByteCounterDelegate *delegate) = 0;
 
     // factory
     // return appropriate concrete impl
     // caller owns returned ByteCounter and is responsible for deleting it
     static ByteCounter* NewByteCounter(const std::string& interface);
 };
 
-// interface for delegates
+// interface to be implemented by delegates
 class ByteCounterDelegate {
   public:
     virtual ~ByteCounterDelegate() {}
 
     // called when byte counter is updated
     virtual void OnByteCounterUpdate(const ByteCounter *counter,
                                      uint64 rx_bytes, uint64 tx_bytes) = 0;
 };
 
 }  // namespace cashew
 
 #endif  // SRC_BYTE_COUNTER_H_