Fix up and rename VisibleMargins() in preparation for making use of it.

ui/gfx/paint_vector_icon.cc

Index: ui/gfx/paint_vector_icon.cc
diff --git a/ui/gfx/paint_vector_icon.cc b/ui/gfx/paint_vector_icon.cc
index 7121fde314d5a6933fd93de8c7773f26c82ceac3..438e46e76f5fe01b44ba206701d207234f1dccfd 100644
--- a/ui/gfx/paint_vector_icon.cc
+++ b/ui/gfx/paint_vector_icon.cc
@@ -311,7 +311,8 @@ class VectorIconSource : public CanvasImageSource {
   // CanvasImageSource:
   void Draw(gfx::Canvas* canvas) override {
     if (path_.empty()) {
-      PaintVectorIcon(canvas, id_, size_.width(), color_);
+      if (id_ != VectorIconId::VECTOR_ICON_NONE)
+        PaintVectorIcon(canvas, id_, size_.width(), color_);
       if (badge_id_ != VectorIconId::VECTOR_ICON_NONE)
         PaintVectorIcon(canvas, badge_id_, size_.width(), color_);
     } else {
@@ -385,7 +386,7 @@ void PaintVectorIcon(Canvas* canvas,
                      VectorIconId id,
                      size_t dip_size,
                      SkColor color) {
-  DCHECK(VectorIconId::VECTOR_ICON_NONE != id);
+  DCHECK(id != VectorIconId::VECTOR_ICON_NONE);
   const PathElement* path = canvas->image_scale() == 1.f
                                 ? GetPathForVectorIconAt1xScale(id)
                                 : GetPathForVectorIcon(id);