Shape detection service: Add QR detection in Mac

services/shape_detection/face_detection_impl_mac.h

Index: services/shape_detection/face_detection_impl_mac.h
diff --git a/services/shape_detection/face_detection_impl_mac.h b/services/shape_detection/face_detection_impl_mac.h
index a67118ecf5b50e2d7c3fcd283402c51af6c1b313..88c9ac23de093e6c664e357654625264bafab602 100644
--- a/services/shape_detection/face_detection_impl_mac.h
+++ b/services/shape_detection/face_detection_impl_mac.h
@@ -14,7 +14,8 @@ namespace shape_detection {
 
 class FaceDetectionImplMac : public shape_detection::mojom::FaceDetection {
  public:
-  FaceDetectionImplMac(shape_detection::mojom::FaceDetectorOptionsPtr options);
+  explicit FaceDetectionImplMac(
+      shape_detection::mojom::FaceDetectorOptionsPtr options);
   ~FaceDetectionImplMac() override;
 
   void Detect(mojo::ScopedSharedBufferHandle frame_data,
@@ -24,7 +25,6 @@ class FaceDetectionImplMac : public shape_detection::mojom::FaceDetection {
                   callback) override;
 
  private:
-  base::scoped_nsobject<CIContext> context_;
   base::scoped_nsobject<CIDetector> detector_;
 
   DISALLOW_COPY_AND_ASSIGN(FaceDetectionImplMac);