Give Ash material design tray items the correct size and layout

ash/common/shelf/shelf_constants.cc

Index: ash/common/shelf/shelf_constants.cc
diff --git a/ash/common/shelf/shelf_constants.cc b/ash/common/shelf/shelf_constants.cc
index e6a7436cb8d929399d663b10e44beaa8d0bf35f2..04726858c38ba8443169c25d008f04869879db1e 100644
--- a/ash/common/shelf/shelf_constants.cc
+++ b/ash/common/shelf/shelf_constants.cc
@@ -21,6 +21,9 @@ const SkColor kShelfButtonActivatedHighlightColor =
     SkColorSetA(SK_ColorWHITE, 100);
 const float kShelfInkDropVisibleOpacity = 0.2f;
 const SkColor kShelfIconColor = SK_ColorWHITE;
+const int kOverflowButtonSize = 32;
+const int kOverflowButtonCornerRadius = 2;
+const int kAppListButtonRadius = kOverflowButtonSize / 2;
 
 int GetShelfConstant(ShelfConstant shelf_constant) {
   const int kShelfBackgroundAlpha[] = {204, 204, 153};