bluetooth: Fix flaky bluetooth internals browser test.

chrome/browser/resources/bluetooth_internals/snackbar.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Javascript for Snackbar controls, served from chrome://bluetooth-internals/.
  */
 
 cr.define('snackbar', function() {
   /** @typedef {{
@@ skipping 59 matching lines @@
       this.classList.add(options.type);
       this.actionLink_.textContent = options.actionText || 'Dismiss';
 
       this.actionLink_.addEventListener('click', function() {
         if (options.action) options.action();
         this.dismiss();
       }.bind(this));
     },
 
     /**
-     * Shows the Snackbar.
+     * Shows the Snackbar and dispatches the 'showed' event.
      */
     show: function() {
       this.classList.add('open');
       if (Snackbar.hasContentFocus_) this.startTimeout_();
       else this.stopTimeout_();
 
       document.addEventListener('contentfocus', this.boundStartTimeout_);
       document.addEventListener('contentblur', this.boundStopTimeout_);
+      this.dispatchEvent(new CustomEvent('showed'));
     },
 
     /**
      * Dismisses the Snackbar. Once the Snackbar is completely hidden, the
-     * 'dismissed' event is fired.
+     * 'dismissed' event is fired and the returned Promise is resolved. If the
+     * snackbar is already hidden, a resolved Promise is returned.
+     * @return {!Promise}
      */
     dismiss: function() {
-      this.addEventListener('webkitTransitionEnd', function(event) {
-        if (event.propertyName === 'transform')
-          this.dispatchEvent(new CustomEvent('dismissed'));
+      this.stopTimeout_();
+
+      if (!this.classList.contains('open')) {
+        return Promise.resolve();
+      }
+
+      return new Promise(function(resolve) {
+        this.boundOnTransitionEnd_ = this.onTransitionEnd_(resolve).bind(this);
+        this.addEventListener(
+            'webkitTransitionEnd', this.boundOnTransitionEnd_);
+
+        ensureTransitionEndEvent(this, 225);

[scheib, 2017/01/03 22:50:58]

Wny dropping 'SHOW_DURATION'?

[mbrunson, 2017/01/04 00:41:22]

The SHOW_DURATION value was actually the wrong number here. I've made this 225
value a constant in the next patchset.

ensureTransitionEndEvent should fire the webkitTransitionEnd event if the hide
transition doesn't finish 225ms after dismiss() is called, not 5000ms.

+        this.classList.remove('open');
+
+        document.removeEventListener('contentfocus', this.boundStartTimeout_);
+        document.removeEventListener('contentblur', this.boundStopTimeout_);
       }.bind(this));
-
-      ensureTransitionEndEvent(this, SHOW_DURATION);
-      this.classList.remove('open');
-
-      document.removeEventListener('contentfocus', this.boundStartTimeout_);
-      document.removeEventListener('contentblur', this.boundStopTimeout_);
     },
 
     /**
+     * Generates a function that dispatches the 'dismissed' event and removes
+     * itself from the webkitTransitionEnd event when called.
+     * @param {!function()} resolve Promise resolve function.
+     * @return {!function()} Function that is called on webkitTransitionEnd.
+     */
+    onTransitionEnd_: function(resolve) {
+      return function() {
+        this.removeEventListener(
+            'webkitTransitionEnd', this.boundOnTransitionEnd_);
+        this.boundOnTransitionEnd_ = null;
+        this.dispatchEvent(new CustomEvent('dismissed'));
+        resolve();
+      };
+    },
+
+    /**
      * Starts the timeout for dismissing the Snackbar.
      * @private
      */
     startTimeout_: function() {
       this.timeoutId_ = setTimeout(function() {
         this.dismiss();
       }.bind(this), SHOW_DURATION);
     },
 
     /**
@@ skipping 88 matching lines @@
     }, 10);
   };
 
   /**
    * Dismisses the Snackbar currently showing.
    * @param {boolean} clearQueue If true, clears the Snackbar queue before
    *     dismissing.
    */
   Snackbar.dismiss = function(clearQueue) {
     if (clearQueue) Snackbar.queue_ = [];
-    if (Snackbar.current_) Snackbar.current_.dismiss();
+    if (Snackbar.current_) return Snackbar.current_.dismiss();
+    return Promise.resolve();
   };
 
 
 
   return {
     Snackbar: Snackbar,
     SnackbarType: SnackbarType,
   };
 });