Bluetooth: Add support for pairing display notifications

device/bluetooth/bluetooth_device.h

Index: device/bluetooth/bluetooth_device.h
diff --git a/device/bluetooth/bluetooth_device.h b/device/bluetooth/bluetooth_device.h
index bb363f9083e1880234207a74c1ea0d4616c2c24e..9db044350c803b0078aee541cbc794d919679eab 100644
--- a/device/bluetooth/bluetooth_device.h
+++ b/device/bluetooth/bluetooth_device.h
@@ -123,6 +123,19 @@ class BluetoothDevice {
     virtual void DisplayPasskey(BluetoothDevice* device,
                                 uint32 passkey) = 0;
 
+    // This method will be called when the Bluetooth daemon gets a notification
+    // of a key entered in the device |device| while pairing with the device

[keybuk, 2013/04/17 23:43:37]

nit: "on" the device

[deymo, 2013/04/18 00:26:01]

Done.

+    // using a PIN code or a Passkey. This method will be called only after

[keybuk, 2013/04/17 23:43:37]

nit: paragraph/line break here to de-dense the text

Also this is never called for DisplayPinCode?

[deymo, 2013/04/18 00:26:01]

Right now, with the current BlueZ, no, it is never called. Buuuut, it may be
called if we fix the apple keyboard notification someday.

+    // DisplayPinCode() or DisplayPasskey() is called and before the
+    // corresponding DismissDisplayOrConfirm() is called, but is not warrantied

[keybuk, 2013/04/17 23:43:37]

nit: warranted

[deymo, 2013/04/18 00:26:01]

Done.

+    // to be called on every pairing process that requires a PIN code or a
+    // Passkey because some device may not support this feature.
+    // The |entered| value describes the number of keys entered so far,

[keybuk, 2013/04/17 23:43:37]

nit: paragraph/line break before this one

[deymo, 2013/04/18 00:26:01]

Done.

+    // including the last [enter] key. A first call to DisplayEnteredKeys() with
+    // |entered| as 0 will be effectuated when the device supports this feature.

[keybuk, 2013/04/17 23:43:37]

Isn't this only supported by DisplayPasskey?

Or are you anticipating eventual support for the Apple Keyboard?

[keybuk, 2013/04/17 23:43:37]

nit: replace effectuated with "sent" :)

[deymo, 2013/04/18 00:26:01]

Yes, apple keyboard could be supported eventually and I don't see how ignoring
that support will simplify this interface anyway... so I just added the method
assuming both can be supported by the underlying daemon.

+    virtual void DisplayEnteredKeys(BluetoothDevice* device,
+                                    uint32 entered) = 0;
+
     // This method will be called when the Bluetooth daemon requires that the
     // user confirm that the Passkey |passkey| is displayed on the screen
     // of the device |device| so that it may be authenticated. The delegate