Makes the BattOrConnection read messages instead of bytes

tools/battor_agent/battor_agent.cc

 // 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.
 
 #include "tools/battor_agent/battor_agent.h"
 
 #include "base/bind.h"
 #include "base/thread_task_runner_handle.h"
 #include "tools/battor_agent/battor_connection_impl.h"
 
@@ skipping 96 matching lines @@
       PerformAction(Action::READ_SET_GAIN_ACK);
       break;
     case Action::SEND_START_TRACING:
       PerformAction(Action::READ_START_TRACING_ACK);
       break;
     default:
       CompleteCommand(BATTOR_ERROR_UNEXPECTED_MESSAGE);
   }
 }
 
-void BattOrAgent::OnBytesRead(bool success,
-                              BattOrMessageType type,
-                              scoped_ptr<vector<char>> bytes) {
+void BattOrAgent::OnMessageRead(bool success,
+                                BattOrMessageType type,
+                                scoped_ptr<vector<char>> bytes) {
   if (!success) {
     CompleteCommand(BATTOR_ERROR_RECEIVE_ERROR);
     return;
   }
 
   switch (last_action_) {
     case Action::READ_INIT_ACK:
       if (!IsAckOfControlCommand(type, BATTOR_CONTROL_MESSAGE_TYPE_INIT,
                                  *bytes)) {
         CompleteCommand(BATTOR_ERROR_UNEXPECTED_MESSAGE);
@@ skipping 45 matching lines @@
       SendControlMessage(BATTOR_CONTROL_MESSAGE_TYPE_RESET, 0, 0);
       break;
     case Action::SEND_INIT:
       // After resetting the BattOr, we need to make sure to flush the serial
       // stream. Strange data may have been written into it during the reset.
       connection_->Flush();
 
       SendControlMessage(BATTOR_CONTROL_MESSAGE_TYPE_INIT, 0, 0);
       break;
     case Action::READ_INIT_ACK:
-      connection_->ReadBytes(sizeof(BattOrControlMessageAck));
+      connection_->ReadMessage(sizeof(BattOrControlMessageAck));

[nednguyen, 2016/01/06 22:03:13]

Can yo abstract this to ReadMessage(message_type), and ReadMessage knows how to
compute the message size depending on the message type?
This way, call site do not have to worry about the detail of 
max_data_bytes_to_read not including any start, end, or escape bytes.

[charliea (OOO until 10-5), 2016/01/07 16:00:12]

I like this idea a lot. Done.

       break;
     case Action::SEND_SET_GAIN:
       // Set the BattOr's gain. Setting the gain tells the BattOr the range of
       // power measurements that we expect to see.
       SendControlMessage(BATTOR_CONTROL_MESSAGE_TYPE_SET_GAIN, BATTOR_GAIN_LOW,
                          0);
       break;
     case Action::READ_SET_GAIN_ACK:
-      connection_->ReadBytes(sizeof(BattOrControlMessageAck));
+      connection_->ReadMessage(sizeof(BattOrControlMessageAck));
       break;
     case Action::SEND_START_TRACING:
       SendControlMessage(BATTOR_CONTROL_MESSAGE_TYPE_START_SAMPLING_SD, 0, 0);
       break;
     case Action::READ_START_TRACING_ACK:
-      connection_->ReadBytes(sizeof(BattOrControlMessageAck));
+      connection_->ReadMessage(sizeof(BattOrControlMessageAck));
       break;
     case Action::INVALID:
       NOTREACHED();
   }
 }
 
 void BattOrAgent::PerformDelayedAction(Action action, base::TimeDelta delay) {
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE, base::Bind(&BattOrAgent::PerformAction, AsWeakPtr(), action),
       delay);
@@ skipping 15 matching lines @@
       break;
     case Command::INVALID:
       NOTREACHED();
   }
 
   last_action_ = Action::INVALID;
   command_ = Command::INVALID;
 }
 
 }  // namespace battor