Add GetConnectionInfo function for BluetoothDevice, replacing the existing

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 3c273ffcb775c01c8cb7a66118471e08c03b4778..d24f1123889f0c40cb73d377552eeac85a8e32de 100644
--- a/device/bluetooth/bluetooth_device.h
+++ b/device/bluetooth/bluetooth_device.h
@@ -68,6 +68,22 @@ class BluetoothDevice {
   // The value returned if the RSSI or transmit power cannot be read.
   static const int kUnknownPower = 127;
 
+  struct ConnectionInfo {
+    int rssi;
+    int transmit_power;
+    int max_transmit_power;
+
+    ConnectionInfo()
+        : rssi(kUnknownPower),
+          transmit_power(kUnknownPower),
+          max_transmit_power(kUnknownPower) {}
+
+    ConnectionInfo(int rssi, int transmit_power, int max_transmit_power)
+        : rssi(rssi),
+          transmit_power(transmit_power),
+          max_transmit_power(max_transmit_power) {}

[armansito, 2015/01/06 20:36:07]

Even though this is a simple struct, I would move the method definitions to the
source file. Also make sure to declare a destructor.

[Tim Song, 2015/01/06 22:30:51]

Done.

+  };
+
   // Possible errors passed back to an error callback function in case of a
   // failed call to Connect().
   enum ConnectErrorCode {
@@ -203,28 +219,6 @@ class BluetoothDevice {
   // DEVICE_PERIPHERAL.
   DeviceType GetDeviceType() const;
 
-  // Gets the "received signal strength indication" (RSSI) of the current
-  // connection to the device. The RSSI indicates the power present in the
-  // received radio signal, measured in dBm, to a resolution of 1dBm. Larger
-  // (typically, less negative) values indicate a stronger signal.
-  // If the device is not currently connected, then returns the RSSI read from
-  // the last inquiry that returned the device, where available. In case of an
-  // error, returns |kUnknownPower|. Otherwise, returns the connection's RSSI.
-  virtual int GetRSSI() const = 0;
-
-  // These two methods are used to read the current or maximum transmit power
-  // ("Tx power") of the current connection to the device. The transmit power
-  // indicates the strength of the signal broadcast from the host's Bluetooth
-  // antenna when communicating with the device, measured in dBm, to a
-  // resolution of 1dBm. Larger (typically, less negative) values
-  // indicate a stronger signal.
-  // It is only meaningful to call this method when there is a connection
-  // established to the device. If there is no connection, or in case of an
-  // error, returns |kUnknownPower|. Otherwise, returns the connection's
-  // transmit power.
-  virtual int GetCurrentHostTransmitPower() const = 0;
-  virtual int GetMaximumHostTransmitPower() const = 0;
-
   // Indicates whether the device is known to support pairing based on its
   // device class and address.
   bool IsPairable() const;
@@ -269,6 +263,8 @@ class BluetoothDevice {
   // In the success case this callback is not called.
   typedef base::Callback<void(enum ConnectErrorCode)> ConnectErrorCallback;
 
+  typedef base::Callback<void(const ConnectionInfo&)> ConnectionInfoCallback;
+
   // Indicates whether the device is currently pairing and expecting a
   // PIN Code to be returned.
   virtual bool ExpectingPinCode() const = 0;
@@ -281,6 +277,21 @@ class BluetoothDevice {
   // confirmation of a displayed passkey.
   virtual bool ExpectingConfirmation() const = 0;
 
+  // Returns the RSSI and TX power of the active connection to the device:
+  //
+  // The RSSI indicates the power present in the received radio signal, measured
+  // in dBm, to a resolution of 1dBm. Larger (typically, less negative) values
+  // indicate a stronger signal.
+  //
+  // The transmit power indicates the strength of the signal broadcast from the
+  // host's Bluetooth antenna when communicating with the device, measured in
+  // dBm, to a resolution of 1dBm. Larger (typically, less negative) values
+  // indicate a stronger signal.
+  //
+  // If the device isn't connected, then the ConnectionInfo struct passed into
+  // the callback will filled by |kUnknownPower|.

[armansito, 2015/01/06 20:36:07]

nit: s/will filled by/will be populated with/

[Tim Song, 2015/01/06 22:30:51]

Done.

+  virtual void GetConnectionInfo(const ConnectionInfoCallback& callback) = 0;

[armansito, 2015/01/06 20:36:08]

Maybe it's better to have an ErrorCallback instead of returning an invalid
ConnectionInfo struct in the case of failure? Up to you.

[Tim Song, 2015/01/06 22:30:51]

The underlying dbus/mac apis might return invalid values, so I think we should
try to have one consistent error state.

[armansito, 2015/01/06 22:39:29]

That's what I figured why you chose to do it this way :) sgtm

+
   // Initiates a connection to the device, pairing first if necessary.
   //
   // Method calls will be made on the supplied object |pairing_delegate|
@@ -384,12 +395,6 @@ class BluetoothDevice {
       const GattConnectionCallback& callback,
       const ConnectErrorCallback& error_callback) = 0;
 
-  // Starts monitoring the connection properties, RSSI and TX power. These
-  // properties will be tracked, and updated when their values change. Exactly
-  // one of |callback| or |error_callback| will be run.
-  virtual void StartConnectionMonitor(const base::Closure& callback,
-                                      const ErrorCallback& error_callback) = 0;
-
   // Returns the list of discovered GATT services.
   virtual std::vector<BluetoothGattService*> GetGattServices() const;