Add Device Policy Handler for Bluetooth, and allow disabling the Bluetooth adapter on Chrome OS

chrome/browser/chromeos/policy/bluetooth_policy_handler.h

+// Copyright (c) 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_POLICY_BLUETOOTH_POLICY_HANDLER_H_
+#define CHROME_BROWSER_CHROMEOS_POLICY_BLUETOOTH_POLICY_HANDLER_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/chromeos/settings/cros_settings.h"
+#include "device/bluetooth/bluetooth_adapter.h"
+
+namespace chromeos {
+// This class observes the device setting |DeviceAllowBluetooth|. Changes to
+// this policy are communicated to SetBluetoothPolicy method by calling

[Andrew T Wilson (Slow), 2016/04/13 13:55:10]

This doesn't actually explain what the class does. The first sentence is great
("observes the device setting |DeviceAllowBluetooth|". But the next sentence
should explain what it does after that in terms of functionality - telling the
reader that various private member functions are called isn't very useful.

Instead, maybe something like "This class observes the device setting
|DeviceAllowBluetooth|, and calls BluetoothAdapter::SetDisabled() appropriately
based on the value of that setting." - that way the reader knows exactly what
this object does: it maps policy values into API calls into BluetoothAdapter.
Whether various internal member functions are called should not really be part
of the public class documentation.

[Ivan Šandrk, 2016/04/13 17:19:04]

Done.

+// OnBluetoothPolicyChanged method with the new state of the policy.
+class BluetoothPolicyHandler {
+ public:
+  explicit BluetoothPolicyHandler(CrosSettings* cros_settings);
+  ~BluetoothPolicyHandler();
+
+ private:
+  // Once a trusted set of policies is established, this function calls
+  // |SetDisabled| with the trusted state of the |DeviceAllowBluetooth| policy
+  // through helper function |SetBluetoothPolicy|.
+  void OnBluetoothPolicyChanged();
+
+  // Helper function used in device::BluetoothAdapterFactory::GetAdapter
+  // callback, this is the function that actually calls |SetDisabled|.
+  void SetBluetoothPolicy(bool bt_disabled,
+                          scoped_refptr<device::BluetoothAdapter> adapter);
+
+  CrosSettings* cros_settings_;
+  scoped_ptr<CrosSettings::ObserverSubscription> bluetooth_policy_subscription_;
+  base::WeakPtrFactory<BluetoothPolicyHandler> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(BluetoothPolicyHandler);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_POLICY_BLUETOOTH_POLICY_HANDLER_H_