[Chrome OS MD] Update the color of update button and improve its appearance

ash/resources/vector_icons/system_menu_update.1x.icon

Index: ash/resources/vector_icons/system_menu_update.1x.icon
diff --git a/ash/resources/vector_icons/system_menu_update.1x.icon b/ash/resources/vector_icons/system_menu_update.1x.icon
index a5a9a9cb6db9a8299f7a4f39a45ef8a6599875b9..8a65ffb84a21f92ae4a3e14c1ee641ef5a6747e4 100644
--- a/ash/resources/vector_icons/system_menu_update.1x.icon
+++ b/ash/resources/vector_icons/system_menu_update.1x.icon
@@ -4,16 +4,18 @@
 
 CANVAS_DIMENSIONS, 20,
 MOVE_TO, 10, 18,
-R_ARC_TO, 8, 8, 0, 1, 0, 0, -16,
-R_ARC_TO, 8, 8, 0, 0, 0, 0, 16,
+R_CUBIC_TO, 4.42f, 0, 8, -3.58f, 8, -8,
+R_CUBIC_TO, 0, -4.42f, -3.58f, -8, -8, -8,
+R_CUBIC_TO, -4.42f, 0, -8, 3.58f, -8, 8,
+R_CUBIC_TO, 0, 4.42f, 3.58f, 8, 8, 8,
 CLOSE,
-R_MOVE_TO, -1, -5,
-R_H_LINE_TO, 2,
-R_V_LINE_TO, -2,
-R_H_LINE_TO, 2,
-R_LINE_TO, -3, -4,
-R_LINE_TO, -3, 4,
-R_H_LINE_TO, 2,
-R_V_LINE_TO, 2,
+R_MOVE_TO, -2, -4,
+R_H_LINE_TO, 4,
+R_V_LINE_TO, -3,
+R_H_LINE_TO, 3,
+R_LINE_TO, -5, -6,
+R_LINE_TO, -5, 6,
+R_H_LINE_TO, 3,
+R_V_LINE_TO, 3,
 CLOSE,
 END