Add logging to Bluetooth settings.

- Add logging when users selects the listed devices to connect or
disconnect, and when connection error is shown
- Update the event for the top level bluetooth master switch toggle to
have its own event.

Change-Id: I58f21256fdd07fad9d733ff987ff38df1148f4f8
Fix: 35065258
Test: make RunSettingsRoboTests

src/com/android/settings/bluetooth/BluetoothSettings.java

@@ -153,7 +153,8 @@ public final class BluetoothSettings extends DeviceListPreferenceFragment implem
         mSwitchBar = activity.getSwitchBar();
 
         mBluetoothEnabler = new BluetoothEnabler(activity, new SwitchBarController(mSwitchBar),
-            mMetricsFeatureProvider, Utils.getLocalBtManager(activity));
+            mMetricsFeatureProvider, Utils.getLocalBtManager(activity),
+            MetricsEvent.ACTION_BLUETOOTH_TOGGLE);
         mBluetoothEnabler.setupSwitchController();
     }