Wire up an api to darken screen for accessibility

chrome/renderer/resources/extensions/automation/automation_node.js

Index: chrome/renderer/resources/extensions/automation/automation_node.js
diff --git a/chrome/renderer/resources/extensions/automation/automation_node.js b/chrome/renderer/resources/extensions/automation/automation_node.js
index 15b722570a53cce1a08e750c559672d4226247d3..a00bd8542f207d79bfdd037876a97c06afdeb184 100644
--- a/chrome/renderer/resources/extensions/automation/automation_node.js
+++ b/chrome/renderer/resources/extensions/automation/automation_node.js
@@ -420,6 +420,10 @@ AutomationNodeImpl.prototype = {
     this.performAction_('suspendMedia');
   },
 
+  toggleDarkenScreen: function(toggle) {
+    this.performAction_('toggleDarkenScreen', { darkenScreen: toggle });
+  },
+
   domQuerySelector: function(selector, callback) {
     if (!this.rootImpl)
       callback();
@@ -1117,6 +1121,9 @@ function AutomationRootNode() {
 }
 utils.expose(AutomationRootNode, AutomationRootNodeImpl, {
   superclass: AutomationNode,
+  functions: [
+    'toggleDarkenScreen'
+  ],
   readonly: [
     'chromeChannel',
     'docTitle',