MD Settings: Search engine dialog, tweak logic to show "input invalid".

chrome/browser/resources/settings/search_engines_page/search_engine_dialog.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.
 
 /**
  * @fileoverview 'settings-search-engine-dialog' is a component for adding
  * or editing a search engine entry.
  */
 Polymer({
   is: 'settings-search-engine-dialog',
@@ skipping 80 matching lines @@
     this.$.dialog.close();
   },
 
   /**
    * @param {!Event} event
    * @private
    */
   validate_: function(event) {
     var inputElement = Polymer.dom(event).localTarget;
 
+    // If element is empty, disable the action button, but don't show the red
+    // invalid message.
+    if (inputElement.value == '') {
+      inputElement.invalid = false;
+      this.updateActionButtonState_();
+      return;
+    }
+
     this.browserProxy_.validateSearchEngineInput(
         inputElement.id, inputElement.value).then(function(isValid) {
       inputElement.invalid = !isValid;
       this.updateActionButtonState_();
     }.bind(this));
   },
 
   /** @private */
   updateActionButtonState_: function() {
     var allValid = [
       this.$.searchEngine, this.$.keyword, this.$.queryUrl
     ].every(function(inputElement) {
-      return !inputElement.invalid && inputElement.value.length != 0;
+      return !inputElement.invalid && inputElement.value.length > 0;
     });
     this.$.actionButton.disabled = !allValid;
   },
 });