device/bluetooth: Add BluetoothBatteryClient

This CL adds BluetoothBatteryClient which is a proxy to BlueZ's
org.bluez.Battery1 interface. Future CLs will interact with this new
interface to get battery level of Bluetooth devices and store the
value to BluetoothDevice object.

Battery API Doc:
https://chromium.googlesource.com/chromiumos/third_party/bluez/+/refs/heads/chromeos-5.54/doc/battery-api.txt

Bug: b:160905767
Change-Id: I2bee100b25518b48a296b87657026769058384d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2296266
Commit-Queue: Sonny Sasaka <sonnysasaka@chromium.org>
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789676}

device/bluetooth/BUILD.gn

@@ -324,6 +324,8 @@ component("bluetooth") {
         "dbus/bluetooth_agent_manager_client.h",
         "dbus/bluetooth_agent_service_provider.cc",
         "dbus/bluetooth_agent_service_provider.h",
+        "dbus/bluetooth_battery_client.cc",
+        "dbus/bluetooth_battery_client.h",
         "dbus/bluetooth_dbus_client_bundle.cc",
         "dbus/bluetooth_dbus_client_bundle.h",
         "dbus/bluetooth_debug_manager_client.cc",
@@ -400,6 +402,8 @@ component("bluetooth") {
           "dbus/fake_bluetooth_agent_manager_client.h",
           "dbus/fake_bluetooth_agent_service_provider.cc",
           "dbus/fake_bluetooth_agent_service_provider.h",
+          "dbus/fake_bluetooth_battery_client.cc",
+          "dbus/fake_bluetooth_battery_client.h",
           "dbus/fake_bluetooth_debug_manager_client.cc",
           "dbus/fake_bluetooth_debug_manager_client.h",
           "dbus/fake_bluetooth_device_client.cc",

device/bluetooth/bluez/bluetooth_adapter_bluez.cc

@@ -40,6 +40,7 @@
 #include "device/bluetooth/dbus/bluetooth_adapter_client.h"
 #include "device/bluetooth/dbus/bluetooth_agent_manager_client.h"
 #include "device/bluetooth/dbus/bluetooth_agent_service_provider.h"
+#include "device/bluetooth/dbus/bluetooth_battery_client.h"
 #include "device/bluetooth/dbus/bluetooth_device_client.h"
 #include "device/bluetooth/dbus/bluetooth_gatt_application_service_provider.h"
 #include "device/bluetooth/dbus/bluetooth_gatt_manager_client.h"
@@ -244,6 +245,8 @@ void BluetoothAdapterBlueZ::Shutdown() {
 
   bluez::BluezDBusManager::Get()->GetBluetoothAdapterClient()->RemoveObserver(
       this);
+  bluez::BluezDBusManager::Get()->GetBluetoothBatteryClient()->RemoveObserver(
+      this);
   bluez::BluezDBusManager::Get()->GetBluetoothDeviceClient()->RemoveObserver(
       this);
   bluez::BluezDBusManager::Get()->GetBluetoothInputClient()->RemoveObserver(
@@ -282,6 +285,8 @@ void BluetoothAdapterBlueZ::Init() {
 
   bluez::BluezDBusManager::Get()->GetBluetoothAdapterClient()->AddObserver(
       this);
+  bluez::BluezDBusManager::Get()->GetBluetoothBatteryClient()->AddObserver(
+      this);
   bluez::BluezDBusManager::Get()->GetBluetoothDeviceClient()->AddObserver(this);
   bluez::BluezDBusManager::Get()->GetBluetoothInputClient()->AddObserver(this);
   bluez::BluezDBusManager::Get()->GetBluetoothAgentManagerClient()->AddObserver(
@@ -641,6 +646,21 @@ void BluetoothAdapterBlueZ::AdapterPropertyChanged(
   }
 }
 
+void BluetoothAdapterBlueZ::BatteryAdded(const dbus::ObjectPath& object_path) {
+  // TODO(b/160905767): Handle it by updating device battery percentage field.
+}
+
+void BluetoothAdapterBlueZ::BatteryRemoved(
+    const dbus::ObjectPath& object_path) {
+  // TODO(b/160905767): Handle it by updating device battery percentage field.
+}
+
+void BluetoothAdapterBlueZ::BatteryPropertyChanged(
+    const dbus::ObjectPath& object_path,
+    const std::string& property_name) {
+  // TODO(b/160905767): Handle it by updating device battery percentage field.
+}
+
 void BluetoothAdapterBlueZ::DeviceAdded(const dbus::ObjectPath& object_path) {
   DCHECK(bluez::BluezDBusManager::Get());
   bluez::BluetoothDeviceClient::Properties* properties =

device/bluetooth/bluez/bluetooth_adapter_bluez.h

@@ -28,6 +28,7 @@
 #include "device/bluetooth/dbus/bluetooth_adapter_client.h"
 #include "device/bluetooth/dbus/bluetooth_agent_manager_client.h"
 #include "device/bluetooth/dbus/bluetooth_agent_service_provider.h"
+#include "device/bluetooth/dbus/bluetooth_battery_client.h"
 #include "device/bluetooth/dbus/bluetooth_device_client.h"
 #include "device/bluetooth/dbus/bluetooth_input_client.h"
 #include "device/bluetooth/dbus/bluetooth_profile_manager_client.h"
@@ -77,6 +78,7 @@ class BluetoothPairingBlueZ;
 class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterBlueZ final
     : public device::BluetoothAdapter,
       public bluez::BluetoothAdapterClient::Observer,
+      public bluez::BluetoothBatteryClient::Observer,
       public bluez::BluetoothDeviceClient::Observer,
       public bluez::BluetoothInputClient::Observer,
       public bluez::BluetoothAgentManagerClient::Observer,
@@ -287,6 +289,12 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterBlueZ final
   void AdapterPropertyChanged(const dbus::ObjectPath& object_path,
                               const std::string& property_name) override;
 
+  // bluez::BluetoothBatteryClient::Observer override.
+  void BatteryAdded(const dbus::ObjectPath& object_path) override;
+  void BatteryRemoved(const dbus::ObjectPath& object_path) override;
+  void BatteryPropertyChanged(const dbus::ObjectPath& object_path,
+                              const std::string& property_name) override;
+
   // bluez::BluetoothDeviceClient::Observer override.
   void DeviceAdded(const dbus::ObjectPath& object_path) override;
   void DeviceRemoved(const dbus::ObjectPath& object_path) override;

device/bluetooth/dbus/bluetooth_battery_client.cc

+// Copyright 2020 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/bluetooth_battery_client.h"
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/stl_util.h"
+#include "dbus/bus.h"
+#include "dbus/message.h"
+#include "dbus/object_manager.h"
+#include "dbus/object_proxy.h"
+#include "third_party/cros_system_api/dbus/service_constants.h"
+
+namespace bluez {
+
+BluetoothBatteryClient::Properties::Properties(
+    dbus::ObjectProxy* object_proxy,
+    const std::string& interface_name,
+    const PropertyChangedCallback& callback)
+    : dbus::PropertySet(object_proxy, interface_name, callback) {
+  RegisterProperty(bluetooth_battery::kPercentageProperty, &percentage);
+}
+
+BluetoothBatteryClient::Properties::~Properties() = default;
+
+// The BluetoothBatteryClient implementation used in production.
+class BluetoothBatteryClientImpl : public BluetoothBatteryClient,
+                                   public dbus::ObjectManager::Interface {
+ public:
+  BluetoothBatteryClientImpl() = default;
+
+  ~BluetoothBatteryClientImpl() override {
+    // There is an instance of this client that is created but not initialized
+    // on Linux. See 'Alternate D-Bus Client' note in bluez_dbus_manager.h.
+    if (object_manager_) {
+      object_manager_->UnregisterInterface(
+          bluetooth_adapter::kBluetoothAdapterInterface);
+    }
+  }
+
+  // BluetoothBatteryClient override.
+  void AddObserver(BluetoothBatteryClient::Observer* observer) override {
+    DCHECK(observer);
+    observers_.AddObserver(observer);
+  }
+
+  // BluetoothBatteryClient override.
+  void RemoveObserver(BluetoothBatteryClient::Observer* observer) override {
+    DCHECK(observer);
+    observers_.RemoveObserver(observer);
+  }
+
+  // dbus::ObjectManager::Interface override.
+  dbus::PropertySet* CreateProperties(
+      dbus::ObjectProxy* object_proxy,
+      const dbus::ObjectPath& object_path,
+      const std::string& interface_name) override {
+    return new Properties(
+        object_proxy, interface_name,
+        base::BindRepeating(&BluetoothBatteryClientImpl::OnPropertyChanged,
+                            weak_ptr_factory_.GetWeakPtr(), object_path));
+  }
+
+  // BluetoothBatteryClient override.
+  std::vector<dbus::ObjectPath> GetBatteriesForAdapter(
+      const dbus::ObjectPath& adapter_path) override {
+    std::vector<dbus::ObjectPath> object_paths, battery_paths;
+    battery_paths = object_manager_->GetObjectsWithInterface(
+        bluetooth_battery::kBluetoothBatteryInterface);
+    for (const auto& path : battery_paths)
+      object_paths.push_back(path);
+
+    return object_paths;
+  }
+
+  // BluetoothBatteryClient override.
+  Properties* GetProperties(const dbus::ObjectPath& object_path) override {
+    return static_cast<Properties*>(object_manager_->GetProperties(
+        object_path, bluetooth_battery::kBluetoothBatteryInterface));
+  }
+
+ protected:
+  void Init(dbus::Bus* bus,
+            const std::string& bluetooth_service_name) override {
+    object_manager_ = bus->GetObjectManager(
+        bluetooth_service_name,
+        dbus::ObjectPath(
+            bluetooth_object_manager::kBluetoothObjectManagerServicePath));
+    object_manager_->RegisterInterface(
+        bluetooth_battery::kBluetoothBatteryInterface, this);
+  }
+
+ private:
+  // Called by dbus::ObjectManager when an object with the battery interface
+  // is created. Informs observers.
+  void ObjectAdded(const dbus::ObjectPath& object_path,
+                   const std::string& interface_name) override {
+    for (auto& observer : observers_)
+      observer.BatteryAdded(object_path);
+  }
+
+  // Called by dbus::ObjectManager when an object with the battery interface
+  // is removed. Informs observers.
+  void ObjectRemoved(const dbus::ObjectPath& object_path,
+                     const std::string& interface_name) override {
+    for (auto& observer : observers_)
+      observer.BatteryRemoved(object_path);
+  }
+
+  // Called by BluetoothPropertySet when a property value is changed,
+  // either by result of a signal or response to a GetAll() or Get()
+  // call. Informs observers.
+  void OnPropertyChanged(const dbus::ObjectPath& object_path,
+                         const std::string& property_name) {
+    for (auto& observer : observers_)
+      observer.BatteryPropertyChanged(object_path, property_name);
+  }
+
+  dbus::ObjectManager* object_manager_ = nullptr;
+
+  // List of observers interested in event notifications from us.
+  base::ObserverList<BluetoothBatteryClient::Observer>::Unchecked observers_;
+
+  // Weak pointer factory for generating 'this' pointers that might live longer
+  // than we do.
+  // Note: This should remain the last member so it'll be destroyed and
+  // invalidate its weak pointers before any other members are destroyed.
+  base::WeakPtrFactory<BluetoothBatteryClientImpl> weak_ptr_factory_{this};
+
+  DISALLOW_COPY_AND_ASSIGN(BluetoothBatteryClientImpl);
+};
+
+BluetoothBatteryClient::BluetoothBatteryClient() = default;
+
+BluetoothBatteryClient::~BluetoothBatteryClient() = default;
+
+BluetoothBatteryClient* BluetoothBatteryClient::Create() {
+  return new BluetoothBatteryClientImpl();
+}
+
+}  // namespace bluez

device/bluetooth/dbus/bluetooth_battery_client.h

+// Copyright 2020 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.
+
+#ifndef DEVICE_BLUETOOTH_DBUS_BLUETOOTH_BATTERY_CLIENT_H_
+#define DEVICE_BLUETOOTH_DBUS_BLUETOOTH_BATTERY_CLIENT_H_
+
+#include <stdint.h>
+
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/observer_list.h"
+#include "base/values.h"
+#include "dbus/object_path.h"
+#include "dbus/property.h"
+#include "device/bluetooth/bluetooth_export.h"
+#include "device/bluetooth/dbus/bluez_dbus_client.h"
+
+namespace bluez {
+
+// BluetoothBatteryClient is used to communicate with objects on BlueZ's
+// org.bluez.Battery1 interface.
+class DEVICE_BLUETOOTH_EXPORT BluetoothBatteryClient : public BluezDBusClient {
+ public:
+  // Structure of properties on org.bluez.Battery1 interface.
+  struct Properties : public dbus::PropertySet {
+    // The percentage (0-100) of the battery. Read-only.
+    dbus::Property<uint8_t> percentage;
+
+    Properties(dbus::ObjectProxy* object_proxy,
+               const std::string& interface_name,
+               const PropertyChangedCallback& callback);
+    ~Properties() override;
+  };
+
+  // Interface for observing changes from a remote bluetooth battery.
+  class Observer {
+   public:
+    virtual ~Observer() = default;
+
+    // Called when the remote battery with object path |object_path| is added
+    // to the set of known batteries.
+    virtual void BatteryAdded(const dbus::ObjectPath& object_path) {}
+
+    // Called when the remote battery with object path |object_path| is removed
+    // from the set of known batteries.
+    virtual void BatteryRemoved(const dbus::ObjectPath& object_path) {}
+
+    // Called when the battery with object path |object_path| has a
+    // change in value of the property named |property_name|.
+    virtual void BatteryPropertyChanged(const dbus::ObjectPath& object_path,
+                                        const std::string& property_name) {}
+  };
+
+  ~BluetoothBatteryClient() override;
+
+  // Adds and removes observers for events on all remote bluetooth
+  // batteries. Check the |object_path| parameter of observer methods to
+  // determine which battery is issuing the event.
+  virtual void AddObserver(Observer* observer) = 0;
+  virtual void RemoveObserver(Observer* observer) = 0;
+
+  // Returns the list of battery object paths associated with the given adapter
+  // identified by the D-Bus object path |adapter_path|.
+  virtual std::vector<dbus::ObjectPath> GetBatteriesForAdapter(
+      const dbus::ObjectPath& adapter_path) = 0;
+
+  // Obtain the properties for the battery with object path |object_path|,
+  // any values should be copied if needed.
+  virtual Properties* GetProperties(const dbus::ObjectPath& object_path) = 0;
+
+  // Creates the instance.
+  static BluetoothBatteryClient* Create();
+
+ protected:
+  BluetoothBatteryClient();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BluetoothBatteryClient);
+};
+
+}  // namespace bluez
+
+#endif  // DEVICE_BLUETOOTH_DBUS_BLUETOOTH_BATTERY_CLIENT_H_

device/bluetooth/dbus/bluetooth_dbus_client_bundle.cc

@@ -12,6 +12,7 @@
 #include "base/strings/string_util.h"
 #include "device/bluetooth/dbus/bluetooth_adapter_client.h"
 #include "device/bluetooth/dbus/bluetooth_agent_manager_client.h"
+#include "device/bluetooth/dbus/bluetooth_battery_client.h"
 #include "device/bluetooth/dbus/bluetooth_debug_manager_client.h"
 #include "device/bluetooth/dbus/bluetooth_device_client.h"
 #include "device/bluetooth/dbus/bluetooth_gatt_characteristic_client.h"
@@ -23,6 +24,7 @@
 #include "device/bluetooth/dbus/bluetooth_profile_manager_client.h"
 #include "device/bluetooth/dbus/fake_bluetooth_adapter_client.h"
 #include "device/bluetooth/dbus/fake_bluetooth_agent_manager_client.h"
+#include "device/bluetooth/dbus/fake_bluetooth_battery_client.h"
 #include "device/bluetooth/dbus/fake_bluetooth_debug_manager_client.h"
 #include "device/bluetooth/dbus/fake_bluetooth_device_client.h"
 #include "device/bluetooth/dbus/fake_bluetooth_gatt_characteristic_client.h"
@@ -43,6 +45,7 @@ BluetoothDBusClientBundle::BluetoothDBusClientBundle(bool use_fakes)
         BluetoothLEAdvertisingManagerClient::Create());
     bluetooth_agent_manager_client_.reset(
         BluetoothAgentManagerClient::Create());
+    bluetooth_battery_client_.reset(BluetoothBatteryClient::Create());
     bluetooth_debug_manager_client_.reset(
         BluetoothDebugManagerClient::Create());
     bluetooth_device_client_.reset(BluetoothDeviceClient::Create());
@@ -66,6 +69,7 @@ BluetoothDBusClientBundle::BluetoothDBusClientBundle(bool use_fakes)
     bluetooth_le_advertising_manager_client_.reset(
         new FakeBluetoothLEAdvertisingManagerClient);
     bluetooth_agent_manager_client_.reset(new FakeBluetoothAgentManagerClient);
+    bluetooth_battery_client_.reset(new FakeBluetoothBatteryClient);
     bluetooth_debug_manager_client_.reset(new FakeBluetoothDebugManagerClient);
     bluetooth_device_client_.reset(new FakeBluetoothDeviceClient);
     bluetooth_input_client_.reset(new FakeBluetoothInputClient);

device/bluetooth/dbus/bluetooth_dbus_client_bundle.h

@@ -15,6 +15,7 @@ namespace bluez {
 
 class BluetoothAdapterClient;
 class BluetoothAgentManagerClient;
+class BluetoothBatteryClient;
 class BluetoothDebugManagerClient;
 class BluetoothDeviceClient;
 class BluetoothGattCharacteristicClient;
@@ -53,6 +54,10 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDBusClientBundle {
     return bluetooth_debug_manager_client_.get();
   }
 
+  BluetoothBatteryClient* bluetooth_battery_client() {
+    return bluetooth_battery_client_.get();
+  }
+
   BluetoothDeviceClient* bluetooth_device_client() {
     return bluetooth_device_client_.get();
   }
@@ -98,6 +103,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDBusClientBundle {
   std::unique_ptr<BluetoothLEAdvertisingManagerClient>
       bluetooth_le_advertising_manager_client_;
   std::unique_ptr<BluetoothAgentManagerClient> bluetooth_agent_manager_client_;
+  std::unique_ptr<BluetoothBatteryClient> bluetooth_battery_client_;
   std::unique_ptr<BluetoothDebugManagerClient> bluetooth_debug_manager_client_;
   std::unique_ptr<BluetoothDeviceClient> bluetooth_device_client_;
   std::unique_ptr<BluetoothGattCharacteristicClient>

device/bluetooth/dbus/bluez_dbus_manager.cc

@@ -23,6 +23,7 @@
 #include "device/base/features.h"
 #include "device/bluetooth/dbus/bluetooth_adapter_client.h"
 #include "device/bluetooth/dbus/bluetooth_agent_manager_client.h"
+#include "device/bluetooth/dbus/bluetooth_battery_client.h"
 #include "device/bluetooth/dbus/bluetooth_debug_manager_client.h"
 #include "device/bluetooth/dbus/bluetooth_device_client.h"
 #include "device/bluetooth/dbus/bluetooth_gatt_characteristic_client.h"
@@ -115,6 +116,11 @@ bluez::BluezDBusManager::GetBluetoothDebugManagerClient() {
   return client_bundle_->bluetooth_debug_manager_client();
 }
 
+BluetoothBatteryClient* bluez::BluezDBusManager::GetBluetoothBatteryClient() {
+  DCHECK(object_manager_support_known_);
+  return client_bundle_->bluetooth_battery_client();
+}
+
 BluetoothDeviceClient* bluez::BluezDBusManager::GetBluetoothDeviceClient() {
   DCHECK(object_manager_support_known_);
   return client_bundle_->bluetooth_device_client();

device/bluetooth/dbus/bluez_dbus_manager.h

@@ -26,6 +26,7 @@ namespace bluez {
 // Style Note: Clients are sorted by names.
 class BluetoothAdapterClient;
 class BluetoothAgentManagerClient;
+class BluetoothBatteryClient;
 class BluetoothDebugManagerClient;
 class BluetoothDeviceClient;
 class BluetoothGattCharacteristicClient;
@@ -119,6 +120,7 @@ class DEVICE_BLUETOOTH_EXPORT BluezDBusManager {
   BluetoothAdapterClient* GetBluetoothAdapterClient();
   BluetoothLEAdvertisingManagerClient* GetBluetoothLEAdvertisingManagerClient();
   BluetoothAgentManagerClient* GetBluetoothAgentManagerClient();
+  BluetoothBatteryClient* GetBluetoothBatteryClient();
   BluetoothDebugManagerClient* GetBluetoothDebugManagerClient();
   BluetoothDeviceClient* GetBluetoothDeviceClient();
   BluetoothGattCharacteristicClient* GetBluetoothGattCharacteristicClient();

device/bluetooth/dbus/fake_bluetooth_battery_client.cc

+// Copyright (c) 2020 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_battery_client.h"
+
+#include "base/logging.h"
+#include "device/bluetooth/dbus/fake_bluetooth_adapter_client.h"
+#include "third_party/cros_system_api/dbus/service_constants.h"
+
+namespace bluez {
+
+FakeBluetoothBatteryClient::Properties::Properties(
+    const PropertyChangedCallback& callback)
+    : BluetoothBatteryClient::Properties(
+          nullptr,
+          bluetooth_battery::kBluetoothBatteryInterface,
+          callback) {}
+
+FakeBluetoothBatteryClient::Properties::~Properties() = default;
+
+void FakeBluetoothBatteryClient::Properties::Get(
+    dbus::PropertyBase* property,
+    dbus::PropertySet::GetCallback callback) {
+  DVLOG(1) << "Get " << property->name();
+  std::move(callback).Run(false);
+}
+
+void FakeBluetoothBatteryClient::Properties::GetAll() {
+  DVLOG(1) << "GetAll";
+}
+
+void FakeBluetoothBatteryClient::Properties::Set(
+    dbus::PropertyBase* property,
+    dbus::PropertySet::SetCallback callback) {
+  DVLOG(1) << "Set " << property->name();
+  std::move(callback).Run(false);
+}
+
+FakeBluetoothBatteryClient::FakeBluetoothBatteryClient() = default;
+
+FakeBluetoothBatteryClient::~FakeBluetoothBatteryClient() = default;
+
+void FakeBluetoothBatteryClient::Init(
+    dbus::Bus* bus,
+    const std::string& bluetooth_service_name) {}
+
+void FakeBluetoothBatteryClient::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void FakeBluetoothBatteryClient::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+std::vector<dbus::ObjectPath>
+FakeBluetoothBatteryClient::GetBatteriesForAdapter(
+    const dbus::ObjectPath& adapter_path) {
+  if (adapter_path ==
+      dbus::ObjectPath(FakeBluetoothAdapterClient::kAdapterPath))
+    return battery_list_;
+  else
+    return std::vector<dbus::ObjectPath>();
+}
+
+FakeBluetoothBatteryClient::Properties*
+FakeBluetoothBatteryClient::GetProperties(const dbus::ObjectPath& object_path) {
+  PropertiesMap::const_iterator iter = properties_map_.find(object_path);
+  if (iter != properties_map_.end())
+    return iter->second.get();
+  return nullptr;
+}
+
+}  // namespace bluez

device/bluetooth/dbus/fake_bluetooth_battery_client.h

+// Copyright (c) 2020 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.
+
+#ifndef DEVICE_BLUETOOTH_DBUS_FAKE_BLUETOOTH_BATTERY_CLIENT_H_
+#define DEVICE_BLUETOOTH_DBUS_FAKE_BLUETOOTH_BATTERY_CLIENT_H_
+
+#include <cstdint>
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "base/observer_list.h"
+#include "dbus/object_path.h"
+#include "dbus/property.h"
+#include "device/bluetooth/bluetooth_export.h"
+#include "device/bluetooth/dbus/bluetooth_battery_client.h"
+
+namespace bluez {
+
+// FakeBluetoothBatteryClient simulates the behavior of the Bluetooth Daemon
+// battery objects and is used both in test cases in place of a mock and on
+// the Linux desktop.
+class DEVICE_BLUETOOTH_EXPORT FakeBluetoothBatteryClient
+    : public BluetoothBatteryClient {
+ public:
+  struct Properties : public BluetoothBatteryClient::Properties {
+    explicit Properties(const PropertyChangedCallback& callback);
+    ~Properties() override;
+
+    // dbus::PropertySet override
+    void Get(dbus::PropertyBase* property,
+             dbus::PropertySet::GetCallback callback) override;
+    void GetAll() override;
+    void Set(dbus::PropertyBase* property,
+             dbus::PropertySet::SetCallback callback) override;
+  };
+
+  FakeBluetoothBatteryClient();
+  ~FakeBluetoothBatteryClient() override;
+
+  // BluetoothBatteryClient overrides
+  void Init(dbus::Bus* bus, const std::string& bluetooth_service_name) override;
+  void AddObserver(Observer* observer) override;
+  void RemoveObserver(Observer* observer) override;
+  std::vector<dbus::ObjectPath> GetBatteriesForAdapter(
+      const dbus::ObjectPath& adapter_path) override;
+  Properties* GetProperties(const dbus::ObjectPath& object_path) override;
+
+ private:
+  // List of observers interested in event notifications from us.
+  base::ObserverList<Observer>::Unchecked observers_;
+
+  using PropertiesMap =
+      std::map<const dbus::ObjectPath, std::unique_ptr<Properties>>;
+  PropertiesMap properties_map_;
+  std::vector<dbus::ObjectPath> battery_list_;
+};
+
+}  // namespace bluez
+
+#endif  // DEVICE_BLUETOOTH_DBUS_FAKE_BLUETOOTH_DEVICE_CLIENT_H_