feat(ScreenObtainer): trigger external for not verified site

Will trigger external installation also for sites that are not the main
whitelisted domain. This allows to reuse one extension for many sites
(they still have to be on the whitelist, but only one can be "main").

modules/RTC/ScreenObtainer.js

@@ -50,6 +50,15 @@ const CHROME_EXTENSION_POPUP_ERROR
 const CHROME_EXTENSION_IFRAME_ERROR
     = 'Chrome Web Store installations can only be started by the top frame.';
 
+/**
+ * The error returned by chrome when trying to start inline installation
+ * not from the "main" whitelisted site.
+ * @type {string}
+ */
+const CHROME_EXTENSION_INLINE_ERROR
+    = 'Installs can only be initiated by one of'
+        + ' the Chrome Web Store item\'s verified sites.';
+
 /**
  * The error message returned by chrome when the extension is installed.
  */
@@ -407,7 +416,8 @@ const ScreenObtainer = {
         const webStoreInstallUrl = getWebStoreInstallUrl(this.options);
 
         if ((CHROME_EXTENSION_POPUP_ERROR === e
-             || CHROME_EXTENSION_IFRAME_ERROR === e)
+             || CHROME_EXTENSION_IFRAME_ERROR === e
+             || CHROME_EXTENSION_INLINE_ERROR === e)
                 && options.interval > 0
                 && typeof options.checkAgain === 'function'
                 && typeof options.listener === 'function') {