add missing property

manifest.json

@@ -119,7 +119,8 @@
 	"browser_specific_settings": {
 		"gecko": {
 			"id": "{531906d3-e22f-4a6c-a102-8057b88a1a63}"
-		}
+		},
+		"gecko_android": {}
 	},
 	"devtools_page": "src/core/devtools/devtools.html",
 	"incognito": "spanning",