use all sizes of icon as default icons for the browser action button

manifest.json

@@ -5,6 +5,7 @@
 	"icons": {
 		"16": "extension/ui/resources/icon_16.png",
 		"48": "extension/ui/resources/icon_48.png",
+		"64": "extension/ui/resources/icon_64.png",
 		"128": "extension/ui/resources/icon_128.png"
 	},
 	"version": "1.9.40",
@@ -94,7 +95,12 @@
 		"open_in_tab": false
 	},
 	"browser_action": {
-		"default_icon": "extension/ui/resources/icon_128.png",
+		"default_icon": {
+			"16": "extension/ui/resources/icon_16.png",
+			"48": "extension/ui/resources/icon_48.png",
+			"64": "extension/ui/resources/icon_64.png",
+			"128": "extension/ui/resources/icon_128.png"
+		},
 		"default_title": "__MSG_buttonDefaultTooltip__"
 	},
 	"commands": {