MD Settings: Adding some unit tests for <settings-main>.

chrome/browser/resources/settings/settings_main/settings_main.js

Index: chrome/browser/resources/settings/settings_main/settings_main.js
diff --git a/chrome/browser/resources/settings/settings_main/settings_main.js b/chrome/browser/resources/settings/settings_main/settings_main.js
index bc621f34e9f9a940584a7f59a267340c3c3c64cf..4684864d1ada00a90473cd36b52a82811198caee 100644
--- a/chrome/browser/resources/settings/settings_main/settings_main.js
+++ b/chrome/browser/resources/settings/settings_main/settings_main.js
@@ -195,6 +195,8 @@ Polymer({
    * @param {string} query

[michaelpg, 2016/07/30 05:38:44]

@return

[dpapad, 2016/08/01 21:23:06]

Done.

    */
   searchContents: function(query) {
+    var promiseResolver = new PromiseResolver();

[michaelpg, 2016/07/30 05:38:44]

this promise/setTimeout business is scary, if we're adding more I'm gonna review
the whole function.

[michaelpg, 2016/07/30 05:38:44]

ok, after looking over it... we're resolving this promise within the same
function, why use a PromiseResolver instead of returning a new Promise directly?

To me, it doesn't look any messier that way and it's one fewer state to keep
track of. Is it just the desire to avoid the extra indent?

[dpapad, 2016/08/01 21:23:06]

Removed PromiseResolver. Yes, it was used to avoid the extra indentation.

+
     this.ensureInDefaultSearchPage_();
     this.toolbarSpinnerActive = true;
 
@@ -213,14 +215,18 @@ Polymer({
               // Nothing to do here. A previous search request was canceled
               // because a new search request was issued before the first one
               // completed.
+              promiseResolver.resolve();

[michaelpg, 2016/07/30 05:38:44]

we should just resolve this before the if so we don't have to have the same line
twice. The promise is always resolved regardless of whether this |if| is true.
(A promise's callbacks execute asynchronously after it is resolved.)

[dpapad, 2016/08/01 21:23:06]

Done.

               return;
             }
 
             this.toolbarSpinnerActive = false;
             this.showNoResultsFound_ =
                 !request.isSame('') && !request.didFindMatches();
+            promiseResolver.resolve();
           }.bind(this));
     }.bind(this), 0);
+
+    return promiseResolver.promise;
   },
 
   /**