Use SK_ColorTRANSPARENT in OverscanCalibrator

Instead of defining a static constant equal to
SkColorSetARGB(0, 0, 0, 0), use the constant defined in SkColor.h

Change-Id: I193fe569569cd9698a0463da9d23f9f9bcff64a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865909
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Auto-Submit: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706933}

ash/display/overscan_calibrator.cc

@@ -124,12 +124,12 @@ void OverscanCalibrator::UpdateInsets(const gfx::Insets& insets) {
 
 void OverscanCalibrator::OnPaintLayer(const ui::PaintContext& context) {
   ui::PaintRecorder recorder(context, calibration_layer_->size());
-  static const SkColor kTransparent = SkColorSetARGB(0, 0, 0, 0);
   gfx::Rect full_bounds = calibration_layer_->bounds();
   gfx::Rect inner_bounds = full_bounds;
   inner_bounds.Inset(insets_);
   recorder.canvas()->FillRect(full_bounds, SK_ColorBLACK);
-  recorder.canvas()->FillRect(inner_bounds, kTransparent, SkBlendMode::kClear);
+  recorder.canvas()->FillRect(inner_bounds, SK_ColorTRANSPARENT,
+                              SkBlendMode::kClear);
 
   gfx::Point center = inner_bounds.CenterPoint();
   int vertical_offset = inner_bounds.height() / 2 - kArrowGapWidth;