fix(screensharing): set error type for cancelling extension install

When cancelling the prompt to install the extension, instead of
treating it as a generic error treat is as the cancel extension
error. This allows existing logic to trigger that will not show
an error message on cancel.

modules/RTC/ScreenObtainer.js

@@ -69,6 +69,13 @@ const CHROME_NO_EXTENSION_ERROR_MSG // eslint-disable-line no-unused-vars
 const CHROME_USER_GESTURE_REQ_ERROR
     = 'Chrome Web Store installations can only be initated by a user gesture.';
 
+/**
+ * The error message returned by chrome when the extension install has been
+ * cancelled by the user.
+ * @type {string}
+ */
+const CHROME_USER_CANCEL_EXTENSION_INSTALL = 'User cancelled install';
+
 /**
  * Handles obtaining a stream from a screen capture on different browsers.
  */
@@ -400,10 +407,15 @@ const ScreenObtainer = {
 
         logger.log(msg, e);
 
-        const error
-            = e === CHROME_USER_GESTURE_REQ_ERROR
-                ? JitsiTrackErrors.CHROME_EXTENSION_USER_GESTURE_REQUIRED
-                : JitsiTrackErrors.CHROME_EXTENSION_INSTALLATION_ERROR;
+        let error;
+
+        if (e === CHROME_USER_CANCEL_EXTENSION_INSTALL) {
+            error = JitsiTrackErrors.CHROME_EXTENSION_USER_CANCELED;
+        } else if (e === CHROME_USER_GESTURE_REQ_ERROR) {
+            error = JitsiTrackErrors.CHROME_EXTENSION_USER_GESTURE_REQUIRED;
+        } else {
+            error = JitsiTrackErrors.CHROME_EXTENSION_INSTALLATION_ERROR;
+        }
 
         failCallback(new JitsiTrackError(error, msg));
     },