Improve AXTree unit tests.

chrome/browser/extensions/api/automation/automation_apitest.cc

 // Copyright 2014 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.
 
 #include "base/files/file_path.h"
 #include "base/path_service.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/extensions/api/automation_internal/automation_util.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
 #include "chrome/browser/extensions/extension_apitest.h"
@@ skipping 213 matching lines @@
 // test extension respectively: see
 // c/t/data/extensions/api_test/automation/tests/generated/generated_trees.js
 class TreeSerializationState {
  public:
   TreeSerializationState()
 #ifdef NDEBUG
       : tree_size(3),
 #else
       : tree_size(2),
 #endif
-        generator(tree_size),
+        generator(tree_size, true),
         num_trees(generator.UniqueTreeCount()),
         tree0_version(0),
         tree1_version(0) {
   }
 
   // Serializes tree and sends it as an accessibility event to the extension.
   void SendDataForTree(const ui::AXTree* tree,
                        TreeSerializer* serializer,
                        int routing_id,
                        BrowserContext* browser_context) {
@@ skipping 273 matching lines @@
       "automationInternal.enableTab",
       FakeAutomationInternalEnableTabFunctionFactory));
   ASSERT_TRUE(extensions::ExtensionFunctionDispatcher::OverrideFunction(
       "automationInternal.performAction",
       FakeAutomationInternalPerformActionFunctionFactory));
   ASSERT_TRUE(RunExtensionSubtest("automation/tests/generated",
                                   "generated_trees.html")) << message_;
 }
 
 }  // namespace extensions