feat(GUI): add webview api version parameter (#1558)

We add the API version sent to the banner via a GET search parameter,
allowing for more intricate control over what data needs or can be sent.

lib/gui/components/safe-webview.js

@@ -29,14 +29,6 @@ const robot = require('../../shared/robot');
 const MODULE_NAME = 'Etcher.Components.SafeWebview';
 const angularSafeWebview = angular.module(MODULE_NAME, []);
 
-/**
- * @summary GET parameter sent to the initial webview source URL
- * @constant
- * @private
- * @type {String}
- */
-const VERSION_PARAM = 'etcher-version';
-
 /**
  * @summary Electron session identifier
  * @constant
@@ -45,6 +37,36 @@ const VERSION_PARAM = 'etcher-version';
  */
 const ELECTRON_SESSION = 'persist:success-banner';
 
+/**
+ * @summary Etcher version search-parameter key
+ * @constant
+ * @private
+ * @type {String}
+ */
+const ETCHER_VERSION_PARAM = 'etcher-version';
+
+/**
+ * @summary API version search-parameter key
+ * @constant
+ * @private
+ * @type {String}
+ */
+const API_VERSION_PARAM = 'api-version';
+
+/**
+ * @summary Webview API version
+ * @constant
+ * @private
+ * @type {String}
+ *
+ * @description
+ * Changing this number represents a departure from an older API and as such
+ * should only be changed when truly necessary as it introduces breaking changes.
+ * This version number is exposed to the banner such that it can determine what
+ * features are safe to utilize.
+ */
+const API_VERSION = 1;
+
 /**
  * @summary Webviews that hide/show depending on the HTTP status returned
  * @type {Object}
@@ -67,8 +89,9 @@ class SafeWebview extends react.PureComponent {
 
     const url = new URL(props.src);
 
-    // We set the version GET parameter here.
+    // We set the version GET parameters here.
-    url.searchParams.set(VERSION_PARAM, packageJSON.version);
+    url.searchParams.set(ETCHER_VERSION_PARAM, packageJSON.version);
+    url.searchParams.set(API_VERSION_PARAM, API_VERSION);
 
     this.entryHref = url.href;