Put all the thresholding code in the same place

This will make it easier to write tests validating the fast version.

Change-Id: I27cc372cc848c495d10a138b3c149d550dc0dad9
diff --git a/aos/vision/tools/jpeg_vision_test.cc b/aos/vision/tools/jpeg_vision_test.cc
index 072b57b..806fd80 100644
--- a/aos/vision/tools/jpeg_vision_test.cc
+++ b/aos/vision/tools/jpeg_vision_test.cc
@@ -74,7 +74,7 @@
     prev_data_ = data.to_string();
 
     // Threshold the image with the given lambda.
-    RangeImage rimg = DoThreshold(img_ptr, [](PixelRef &px) {
+    RangeImage rimg = ThresholdImageWithFunction(img_ptr, [](PixelRef &px) {
       if (px.g > 88) {
         uint8_t min = std::min(px.b, px.r);
         uint8_t max = std::max(px.b, px.r);