Add MD ink drop ripple to app list button

ash/common/shelf/shelf_constants.h

Index: ash/common/shelf/shelf_constants.h
diff --git a/ash/common/shelf/shelf_constants.h b/ash/common/shelf/shelf_constants.h
index aa4feafd27759e1cd4e7d85abe430f64b43287bc..b17eaa8e90b48d12d78d9313026edd4fc98a5ae5 100644
--- a/ash/common/shelf/shelf_constants.h
+++ b/ash/common/shelf/shelf_constants.h
@@ -57,6 +57,9 @@ ASH_EXPORT extern const SkColor kShelfBaseColor;
 // using the material design ripple animation.
 ASH_EXPORT extern const SkColor kShelfButtonActivatedHighlightColor;
 
+// Ink drop color for shelf items.
+extern const SkColor kShelfInkDropBaseColor;
+
 // The foreground color of the icons used in the shelf (launcher,
 // notifications, etc).
 ASH_EXPORT extern const SkColor kShelfIconColor;