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

device/bluetooth/bluetooth_adapter_bluez.h

Index: device/bluetooth/bluetooth_adapter_bluez.h
diff --git a/device/bluetooth/bluetooth_adapter_bluez.h b/device/bluetooth/bluetooth_adapter_bluez.h
index 3d402d4fd1afac5b8da441256531c03e80f63e8d..deba2df891f59b75559cbe26f969330e85363e4c 100644
--- a/device/bluetooth/bluetooth_adapter_bluez.h
+++ b/device/bluetooth/bluetooth_adapter_bluez.h
@@ -86,6 +86,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterBlueZ
                const ErrorCallback& error_callback) override;
   bool IsInitialized() const override;
   bool IsPresent() const override;
+  void SetDisabled(bool disabled) override;
   bool IsPowered() const override;
   void SetPowered(bool powered,
                   const base::Closure& callback,
@@ -346,6 +347,10 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterBlueZ
   // Set in |Shutdown()|, makes IsPresent()| return false.
   bool dbus_is_shutdown_;
 
+  // Set in |SetDisabled()|, makes |IsPresent()| return false
+  // (just disables the interface, doesn't actually shut it down).
+  bool is_disabled_;

[ortuno, 2016/04/13 21:12:21]

I don't think this is the right place to store this. BluetoothAdapter is only
alive as long as someone holds a reference to it. If everyone drops their
references to it and it gets destroyed no one will be able to use the adapter
because the policy will not be set to true again.

[Ivan Šandrk, 2016/04/14 18:08:48]

In my code, I call SetDisabled through
device::BluetoothAdapterFactory::GetAdapter, which fetches the BluetoothAdapter
(and creates one if it doesn't exist) so this shouldn't be an issue.

But you have raised a valid point, something else goes wrong. If the
BluetoothAdapter gets disabled through SetDisabled, then afterwards all the
references go away and BluetoothAdapter is destroyed, then someone uses
BluetoothAdapter again and a new instance gets created, the new instance won't
be disabled.

This may not be a problem tho, as many pieces of code hold references to the
BluetoothAdapter and some have sufficiently long lifetimes (I have to check
this). Maybe the best solution is that I keep a reference to it myself, that way
I'm sure? What is your opinion on this?

[scheib, 2016/04/14 21:41:10]

You'll need to hold a reference to keep it disabled.

[Ivan Šandrk, 2016/04/15 17:32:06]

Done.

+
   // Number of discovery sessions that have been added.
   int num_discovery_sessions_;