Avoid VS 2015 truncation warning

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 56 matching lines @@
     return false;
 
   // The first bytes in the frame contain the frame header.
   const char* frame_ptr = reinterpret_cast<const char*>(msg.data());
   memcpy(frame_header, frame_ptr, sizeof(BattOrFrameHeader));
   frame_ptr += sizeof(BattOrFrameHeader);
 
   // The remaining bytes in the frame contain an array of raw samples.
   // Therefore, the number of samples in the frame should correspond to number
   // of total bytes remaining in the frame.
-  uint8_t samples_in_frame =
+  size_t samples_in_frame =
       (msg.size() - sizeof(BattOrFrameHeader)) / sizeof(RawBattOrSample);
 
   if (samples_in_frame != frame_header->length)
     return false;
 
   samples->resize(samples_in_frame);
   memcpy(samples->data(), frame_ptr,
          samples_in_frame * sizeof(RawBattOrSample));
 
   return true;
@@ skipping 310 matching lines @@
   }
 
   last_action_ = Action::INVALID;
   command_ = Command::INVALID;
   battor_eeprom_.reset();
   calibration_frame_.clear();
   samples_.clear();
 }
 
 }  // namespace battor