Expose device RSSI and Tx power via the chrome.bluetooth API.

device/bluetooth/bluetooth_device.h

 // Copyright (c) 2012 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_BLUETOOTH_DEVICE_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_DEVICE_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 209 matching lines @@
   // be a synthesized string containing the address and localized type name
   // if the device has no obtained name.
   virtual base::string16 GetName() const;
 
   // Returns the type of the device, limited to those we support or are
   // aware of, by decoding the bluetooth class information. The returned
   // values are unique, and do not overlap, so DEVICE_KEYBOARD is not also
   // DEVICE_PERIPHERAL.
   DeviceType GetDeviceType() const;
 
+  // Returns the "received signal strength indication" (RSSI) of the device.
+  // The RSSI is a measurement of the power present in a received radio signal.
+  // Larger (typically, less negative) values indicate a stronger signal.
+  virtual int GetRSSI() const = 0;

[keybuk, 2014/04/23 08:59:19]

Is this the RSSI of inquiry/AD packets - or is this the RSSI of the connection
to the device?

If the latter, then this will require a round-trip to the controller so should
be a method with a callback

[Ilya Sherman, 2014/04/24 06:45:16]

It's the latter.  Do you want me to include a pair of callbacks -- one for
success and one for failure?  FWIW, on Mac, the call is synchronous.  Maybe it
makes sense not to add callbacks until we implement this on a platform that
needs them?  Of course, if you prefer that I add callbacks now, I'm happy to do
that as well.

[keybuk, 2014/04/24 11:25:52]

If synchronous then there should definitely be a callback, you cannae block the
UI thread cap'n

+
   // Indicates whether the device is known to support pairing based on its
   // device class and address.
   bool IsPairable() const;
 
   // Indicates whether the device is paired with the adapter.
   virtual bool IsPaired() const = 0;
 
   // Indicates whether the device is currently connected to the adapter.
   // Note that if IsConnected() is true, does not imply that the device is
   // connected to any application or service. If the device is not paired, it
@@ skipping 148 matching lines @@
 
  private:
   // Returns a localized string containing the device's bluetooth address and
   // a device type for display when |name_| is empty.
   base::string16 GetAddressWithLocalizedDeviceTypeName() const;
 };
 
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_DEVICE_H_