Use container::back() and container::pop_back().

device/bluetooth/dbus/fake_bluetooth_gatt_descriptor_client.cc

 // Copyright 2014 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 "device/bluetooth/dbus/fake_bluetooth_gatt_descriptor_client.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 97 matching lines @@
   if (properties->uuid.value() == kClientCharacteristicConfigurationUUID) {
     BluetoothGattCharacteristicClient::Properties* chrc_props =
         bluez::BluezDBusManager::Get()
             ->GetBluetoothGattCharacteristicClient()
             ->GetProperties(properties->characteristic.value());
     DCHECK(chrc_props);
 
     uint8_t value_byte = chrc_props->notifying.value() ? 0x01 : 0x00;
     const std::vector<uint8_t>& cur_value = properties->value.value();
 
-    if (!cur_value.size() || cur_value[0] != value_byte) {
+    if (cur_value.empty() || cur_value[0] != value_byte) {
       std::vector<uint8_t> value = {value_byte, 0x00};
       properties->value.ReplaceValue(value);
     }
   }
 
   callback.Run(iter->second->properties->value.value());
 }
 
 void FakeBluetoothGattDescriptorClient::WriteValue(
     const dbus::ObjectPath& object_path,
@@ skipping 77 matching lines @@
                     GattDescriptorAdded(object_path));
 }
 
 void FakeBluetoothGattDescriptorClient::NotifyDescriptorRemoved(
     const dbus::ObjectPath& object_path) {
   FOR_EACH_OBSERVER(BluetoothGattDescriptorClient::Observer, observers_,
                     GattDescriptorRemoved(object_path));
 }
 
 }  // namespace bluez