Do not call GetDisplayDevice for older UPower versions.

On Linux, older versions of UPower did not have the GetDisplayDevice
method. Trying to call it generates log spam.

Modernize the modified file with base::MakeUnique while we are here.

BUG=695383

Review-Url: https://codereview.chromium.org/2795713003
Cr-Commit-Position: refs/heads/master@{#463358}

device/battery/battery_status_manager_linux.cc

@@ -61,7 +61,7 @@ base::Version UPowerProperties::daemon_version() {
 
 class UPowerObject {
  public:
-  typedef dbus::PropertySet::PropertyChangedCallback PropertyChangedCallback;
+  using PropertyChangedCallback = dbus::PropertySet::PropertyChangedCallback;
 
   UPowerObject(dbus::Bus* dbus,
                const PropertyChangedCallback property_changed_callback);
@@ -225,7 +225,7 @@ uint32_t BatteryProperties::type(uint32_t default_value) {
 
 class BatteryObject {
  public:
-  typedef dbus::PropertySet::PropertyChangedCallback PropertyChangedCallback;
+  using PropertyChangedCallback = dbus::PropertySet::PropertyChangedCallback;
 
   BatteryObject(dbus::Bus* dbus,
                 const dbus::ObjectPath& device_path,
@@ -334,8 +334,8 @@ class BatteryStatusManagerLinux::BatteryStatusNotificationThread
     if (!system_bus_)
       InitDBus();
 
-    upower_.reset(new UPowerObject(system_bus_.get(),
-                                   UPowerObject::PropertyChangedCallback()));
+    upower_ = base::MakeUnique<UPowerObject>(
+        system_bus_.get(), UPowerObject::PropertyChangedCallback());
     upower_->proxy()->ConnectToSignal(
         kUPowerServiceName, kUPowerSignalDeviceAdded,
         base::Bind(&BatteryStatusNotificationThread::DeviceAdded,
@@ -397,14 +397,14 @@ class BatteryStatusManagerLinux::BatteryStatusNotificationThread
         [&current, this](const dbus::ObjectPath& device_path) {
           if (current && current->proxy()->object_path() == device_path)
             return std::move(current);
-          else
-            return CreateBattery(device_path);
+          return CreateBattery(device_path);
         };
 
-    dbus::ObjectPath display_device_path = upower_->GetDisplayDevice();
+    dbus::ObjectPath display_device_path;
+    if (!IsDaemonVersionBelow_0_99())
+      display_device_path = upower_->GetDisplayDevice();
     if (display_device_path.IsValid()) {
-      std::unique_ptr<BatteryObject> battery =
-          UseCurrentOrCreateBattery(display_device_path);
+      auto battery = UseCurrentOrCreateBattery(display_device_path);
       if (battery->IsValid())
         battery_ = std::move(battery);
     }
@@ -412,9 +412,7 @@ class BatteryStatusManagerLinux::BatteryStatusNotificationThread
     if (!battery_) {
       int num_batteries = 0;
       for (const auto& device_path : upower_->EnumerateDevices()) {
-        std::unique_ptr<BatteryObject> battery =
-            UseCurrentOrCreateBattery(device_path);
-
+        auto battery = UseCurrentOrCreateBattery(device_path);
         if (!battery->IsValid())
           continue;
 
@@ -433,14 +431,14 @@ class BatteryStatusManagerLinux::BatteryStatusNotificationThread
       UpdateNumberBatteriesHistogram(num_batteries);
     }
 
-    if (battery_) {
-      battery_->properties()->ConnectSignals();
-      NotifyBatteryStatus();
-    } else {
+    if (!battery_) {
       callback_.Run(mojom::BatteryStatus());
       return;
     }
 
+    battery_->properties()->ConnectSignals();
+    NotifyBatteryStatus();
+
     if (IsDaemonVersionBelow_0_99()) {
       // UPower Version 0.99 replaced the Changed signal with the
       // PropertyChanged signal. For older versions we need to listen
@@ -476,11 +474,10 @@ class BatteryStatusManagerLinux::BatteryStatusNotificationThread
 
   std::unique_ptr<BatteryObject> CreateBattery(
       const dbus::ObjectPath& device_path) {
-    std::unique_ptr<BatteryObject> battery(new BatteryObject(
+    return base::MakeUnique<BatteryObject>(
         system_bus_.get(), device_path,
         base::Bind(&BatteryStatusNotificationThread::BatteryPropertyChanged,
-                   base::Unretained(this))));
-    return battery;
+                   base::Unretained(this)));
   }
 
   void DeviceAdded(dbus::Signal* signal /* unused */) {
@@ -589,13 +586,14 @@ bool BatteryStatusManagerLinux::StartNotifierThreadIfNecessary() {
     return true;
 
   base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
-  notifier_thread_.reset(new BatteryStatusNotificationThread(callback_));
-  if (!notifier_thread_->StartWithOptions(thread_options)) {
-    notifier_thread_.reset();
+  auto notifier_thread =
+      base::MakeUnique<BatteryStatusNotificationThread>(callback_);
+  if (!notifier_thread->StartWithOptions(thread_options)) {
     LOG(ERROR) << "Could not start the " << kBatteryNotifierThreadName
                << " thread";
     return false;
   }
+  notifier_thread_ = std::move(notifier_thread);
   return true;
 }
 
@@ -608,20 +606,17 @@ std::unique_ptr<BatteryStatusManagerLinux>
 BatteryStatusManagerLinux::CreateForTesting(
     const BatteryStatusService::BatteryUpdateCallback& callback,
     dbus::Bus* bus) {
-  std::unique_ptr<BatteryStatusManagerLinux> manager(
-      new BatteryStatusManagerLinux(callback));
-  if (manager->StartNotifierThreadIfNecessary())
-    manager->notifier_thread_->SetDBusForTesting(bus);
-  else
-    manager.reset();
+  auto manager = base::MakeUnique<BatteryStatusManagerLinux>(callback);
+  if (!manager->StartNotifierThreadIfNecessary())
+    return nullptr;
+  manager->notifier_thread_->SetDBusForTesting(bus);
   return manager;
 }
 
 // static
 std::unique_ptr<BatteryStatusManager> BatteryStatusManager::Create(
     const BatteryStatusService::BatteryUpdateCallback& callback) {
-  return std::unique_ptr<BatteryStatusManager>(
-      new BatteryStatusManagerLinux(callback));
+  return base::MakeUnique<BatteryStatusManagerLinux>(callback);
 }
 
 }  // namespace device