Add methods to TrackRecordingService to start and stop GPS.

No longer unregister location listener before registering it.

MyTracksLib/src/com/google/android/apps/mytracks/services/ITrackRecordingService.aidl

@@ -23,6 +23,16 @@ import com.google.android.apps.mytracks.content.WaypointCreationRequest;
  */
 interface ITrackRecordingService {
 
+  /**
+   * Starts gps.
+   */
+  void startGps();
+
+  /**
+   * Stops gps.
+   */
+  void stopGps();
+
   /**
    * Starts recording a new track.
    *
@@ -85,14 +95,14 @@ interface ITrackRecordingService {
 
   /**
    * Gets the current sensor data. Returns null if there is no data.
-   
+
    * @return a byte array of the binary version of the Sensor.SensorDataSet object.
    */
   byte[] getSensorData();
 
   /**
    * Gets the current sensor manager state.
-   * 
+   *
    * return a Sensor.SensorState enum value.
    */
   int getSensorState();