docs: public void requestCamera(int camera) {
          if (Camera.getNumberOfCameras() == 1) {
              Log.w(TAG, "Ignoring requestCamera: only one device camera available.");
              return;
          }
          mDesiredCamera = camera;
          if (mCamera != null && mDesiredCamera != mCurrentCamera) {
              // Hot swap camera
              mHandler.sendMessage(mHandler.obtainMessage(MSG_RELEASE_CAMERA));
              mHandler.sendMessage(mHandler.obtainMessage(MSG_REOPEN_CAMERA));
          }
      }