[battor agent] Fix the init sequence so it retries inits instead of resets.

tools/battor_agent/battor_connection.h

 // Copyright 2015 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 TOOLS_BATTOR_AGENT_BATTOR_CONNECTION_H_
 #define TOOLS_BATTOR_AGENT_BATTOR_CONNECTION_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 45 matching lines @@
   // protocol.
   virtual void SendBytes(BattOrMessageType type,
                          const void* buffer,
                          size_t bytes_to_send) = 0;
 
   // Gets the next message available from the serial connection, reading the
   // correct number of bytes based on the specified message type, and calls the
   // listener's OnMessageRead() when complete.
   virtual void ReadMessage(BattOrMessageType type) = 0;
 
+  // Cancels the current message read operation.
+  virtual void CancelReadMessage() = 0;
+
   // Flushes the serial connection to the BattOr.
   virtual void Flush() = 0;
 
  protected:
   // The listener receiving the results of the commands being executed.
   Listener* listener_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BattOrConnection);
 };
 
 }  // namespace battor
 
 #endif  // TOOLS_BATTOR_AGENT_BATTOR_CONNECTION_H_