Fix crash of Connected Devices page

Doesn't set the preference context for savedDockUpdater.
We will throw IllegalStateException now.

Change-Id: I684cd2a917ce94e033be578349c3cc1d8650ccea
Fix: 110609074
Test: m -j SettingsRoboTests RunSettingsRoboTests

src/com/android/settings/connecteddevice/PreviouslyConnectedDevicePreferenceController.java

@@ -59,7 +59,9 @@ public class PreviouslyConnectedDevicePreferenceController extends BasePreferenc
         super.displayPreference(screen);
         if (isAvailable()) {
             mPreference = screen.findPreference(getPreferenceKey());
-            mBluetoothDeviceUpdater.setPrefContext(screen.getContext());
+            final Context context = screen.getContext();
+            mBluetoothDeviceUpdater.setPrefContext(context);
+            mSavedDockUpdater.setPreferenceContext(context);
         }
     }