DevTools: empty user agent validation

third_party/WebKit/Source/devtools/front_end/network/NetworkConfigView.js

 // Copyright (c) 2015 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.
 
 /**
  * @constructor
  * @extends {WebInspector.VBox}
  */
 WebInspector.NetworkConfigView = function()
 {
@@ skipping 93 matching lines @@
         for (var userAgentVersion of userAgentDescriptor.values)
             groupElement.appendChild(new Option(userAgentVersion.title, userAgentVersion.value));
     }
 
     userAgentSelectElement.selectedIndex = 0;
 
     var otherUserAgentElement = createElement("input");
     otherUserAgentElement.type = "text";
     otherUserAgentElement.value = userAgentSetting.get();
     otherUserAgentElement.title = userAgentSetting.get();
+    otherUserAgentElement.placeholder = WebInspector.UIString("Enter a custom user agent");
+    otherUserAgentElement.required = true;
 
     settingChanged();
     userAgentSelectElement.addEventListener("change", userAgentSelected, false);
     otherUserAgentElement.addEventListener("input", textChanged, false);
 
     function userAgentSelected()
     {
         var value = userAgentSelectElement.options[userAgentSelectElement.selectedIndex].value;
         if (value !== customOverride.value) {
             userAgentSetting.set(value);
@@ skipping 133 matching lines @@
      * @param {!WebInspector.Context} context
      * @param {string} actionId
      * @return {boolean}
      */
     handleAction: function(context, actionId)
     {
         WebInspector.inspectorView.showViewInDrawer("network.config");
         return true;
     }
 }