Merge pull request #3494 from pkulzc/master

Update object detection with internal changes and remove unused BUILD files.

research/object_detection/protos/multiscale_anchor_generator.proto

@@ -20,4 +20,7 @@ message MultiscaleAnchorGenerator {
 
   // Number of intermediate scale each scale octave
   optional int32 scales_per_octave = 5 [default = 2];
+
+  // Whether to produce anchors in normalized coordinates.
+  optional bool normalize_coordinates = 6 [default = true];
 }