Update shelf spacing in Chrome OS according to the MD specs

ash/shelf/shelf_view.cc

Index: ash/shelf/shelf_view.cc
diff --git a/ash/shelf/shelf_view.cc b/ash/shelf/shelf_view.cc
index d59ff70ae5017f478bb676ccea6c496387cdf5de..50f734bf4fa468464fd22f1fdbe6f719d8463299 100644
--- a/ash/shelf/shelf_view.cc
+++ b/ash/shelf/shelf_view.cc
@@ -812,8 +812,8 @@ void ShelfView::CalculateIdealBounds(IdealBounds* bounds) const {
 
   int x = 0;
   int y = 0;
-  int button_size = kShelfButtonSize;
-  int button_spacing = kShelfButtonSpacing;
+  int button_size = GetShelfLayoutConstant(SHELF_BUTTON_SIZE);
+  int button_spacing = GetShelfLayoutConstant(SHELF_BUTTON_SPACING);
 
   int w = shelf_->PrimaryAxisValue(button_size, width());
   int h = shelf_->PrimaryAxisValue(height(), button_size);
@@ -1412,9 +1412,9 @@ gfx::Rect ShelfView::GetBoundsForDragInsertInScreen() {
 
     if (shelf_->IsHorizontalAlignment()) {
       preferred_size = gfx::Size(last_button_bounds.right() + leading_inset_,
-                                 kShelfSize);
+                                 GetShelfLayoutConstant(SHELF_SIZE));
     } else {
-      preferred_size = gfx::Size(kShelfSize,
+      preferred_size = gfx::Size(GetShelfLayoutConstant(SHELF_SIZE),
                                  last_button_bounds.bottom() + leading_inset_);
     }
   }
@@ -1480,14 +1480,17 @@ gfx::Size ShelfView::GetPreferredSize() const {
     last_button_index--;
 
   const gfx::Rect last_button_bounds =
-      last_button_index  >= first_visible_index_ ?
-          view_model_->ideal_bounds(last_button_index) :
-          gfx::Rect(gfx::Size(kShelfSize, kShelfSize));
+      last_button_index >= first_visible_index_
+          ? view_model_->ideal_bounds(last_button_index)
+          : gfx::Rect(gfx::Size(GetShelfLayoutConstant(SHELF_SIZE),
+                                GetShelfLayoutConstant(SHELF_SIZE)));
 
   if (shelf_->IsHorizontalAlignment())
-    return gfx::Size(last_button_bounds.right() + leading_inset_, kShelfSize);
+    return gfx::Size(last_button_bounds.right() + leading_inset_,
+                     GetShelfLayoutConstant(SHELF_SIZE));
 
-  return gfx::Size(kShelfSize, last_button_bounds.bottom() + leading_inset_);
+  return gfx::Size(GetShelfLayoutConstant(SHELF_SIZE),
+                   last_button_bounds.bottom() + leading_inset_);
 }
 
 void ShelfView::OnBoundsChanged(const gfx::Rect& previous_bounds) {