Camera: Add hidden experimental tearDown method.

Bug: 18949148
Change-Id: Ie86ec7d1ec3db54e1154563b2339a208a935f849
diff --git a/services/camera/libcameraservice/device2/Camera2Device.h b/services/camera/libcameraservice/device2/Camera2Device.h
index c9f3a2c..34c1ded 100644
--- a/services/camera/libcameraservice/device2/Camera2Device.h
+++ b/services/camera/libcameraservice/device2/Camera2Device.h
@@ -85,8 +85,9 @@
             buffer_handle_t *buffer, wp<BufferReleasedListener> listener);
     // Flush implemented as just a wait
     virtual status_t flush(int64_t *lastFrameNumber = NULL);
-    // Prepare is a no-op
+    // Prepare and tearDown are no-ops
     virtual status_t prepare(int streamId);
+    virtual status_t tearDown(int streamId);
 
     virtual uint32_t getDeviceVersion();
     virtual ssize_t getJpegBufferSize(uint32_t width, uint32_t height) const;