Address eye dropper UI feedback.

This CL fixes the following eye dropper UI issues:
- center square for the eye dropper border should be black & white
double strokes
- macOS pre-10.15 eye dropper size should be a 9x9 square.

Bug: 1130418, 1130415
Change-Id: I8ae3c22b01aef0ebd4bbf94a9e31d0192d3f58a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2424668Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Ionel Popescu <iopopesc@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#809657}

chrome/browser/ui/views/eye_dropper/eye_dropper_view.cc

@@ -186,10 +186,17 @@ void EyeDropperView::OnPaint(gfx::Canvas* view_canvas) {
         flags);
   }
 
-  // Paint central pixel in red.
+  // Paint central pixel.
   gfx::RectF pixel((size().width() - kPixelSize) / 2,
                    (size().height() - kPixelSize) / 2, kPixelSize, kPixelSize);
-  flags.setColor(SK_ColorRED);
+  flags.setAntiAlias(true);
+  flags.setColor(SK_ColorWHITE);
+  flags.setStrokeWidth(2);
+  pixel.Inset(-0.5f, -0.5f);
+  view_canvas->DrawRect(pixel, flags);
+  flags.setColor(SK_ColorBLACK);
+  flags.setStrokeWidth(1);
+  pixel.Inset(0.5f, 0.5f);
   view_canvas->DrawRect(pixel, flags);
 
   // Paint outline.

chrome/browser/ui/views/eye_dropper/eye_dropper_view_mac.mm

@@ -94,11 +94,11 @@ void EyeDropperView::ShowCursor() {
 }
 
 gfx::Size EyeDropperView::GetSize() const {
-  return gfx::Size(70, 70);
+  return gfx::Size(90, 90);
 }
 
 float EyeDropperView::GetDiameter() const {
-  return 70;
+  return 90;
 }
 
 std::unique_ptr<content::EyeDropper> ShowEyeDropper(