Mojo C++ bindings: switch device/serial mojom target to use STL types.

tools/battor_agent/battor_finder.cc

 // Copyright 2016 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_finder.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "device/serial/serial.mojom.h"
 #include "device/serial/serial_device_enumerator.h"
@@ skipping 20 matching lines @@
   mojo::Array<device::serial::DeviceInfoPtr> devices =
       serial_device_enumerator->GetDevices();
 
   std::string switch_specified_path =
       base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
           kBattOrPathSwitch);
   if (switch_specified_path.empty()) {
     // If we have no switch-specified path, look for a device with the right
     // display name.
     for (size_t i = 0; i < devices.size(); i++) {
-      std::string display_name = devices[i]->display_name.get();
+      if (!devices[i]->display_name)
+        continue;
+      const auto& display_name = devices[i]->display_name.value();
       if (display_name.find(kBattOrDisplayNamePrefix) != std::string::npos) {
         LOG(INFO) << "Found BattOr with display name " << display_name
                   << " at path " << devices[i]->path;
         return devices[i]->path;
       }
     }
   } else {
     // If we have a switch-specified path, make sure it actually exists before
     // returning it.
     for (size_t i = 0; i < devices.size(); i++) {
       if (devices[i]->path == switch_specified_path)
         return switch_specified_path;
     }
   }
 
   return std::string();
 }
 
 }  // namespace battor