Ensure fake alert window attached to AXAura tree and refine alert dialog output

chrome/browser/ui/ash/accessibility/ax_tree_source_aura_unittest.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 <stddef.h>
 
 #include <vector>
 
 #include "ash/test/ash_test_base.h"
 #include "base/macros.h"
@@ skipping 126 matching lines @@
 }
 
 TEST_F(AXTreeSourceAuraTest, Serialize) {
   AXTreeSourceAura ax_tree;
   AuraAXTreeSerializer ax_serializer(&ax_tree);
   ui::AXTreeUpdate out_update;
 
   // This is the initial serialization.
   ax_serializer.SerializeChanges(ax_tree.GetRoot(), &out_update);
 
-  // The update should just be the desktop node since no events have been fired
-  // on any controls, so no windows have been cached.
-  ASSERT_EQ(1U, out_update.nodes.size());
+  // The update should just be the desktop node and the fake alert window we use
+  // to handle posting text alerts.
+  ASSERT_EQ(2U, out_update.nodes.size());
 
   // Try removing some child views and re-adding which should fire some events.
   content_->RemoveAllChildViews(false /* delete_children */);
   content_->AddChildView(textfield_);
 
   // Grab the textfield since serialization only walks up the tree (not down
   // from root).
   AXAuraObjWrapper* textfield_wrapper =
       AXAuraObjCache::GetInstance()->GetOrCreate(textfield_);
 
   // Now, re-serialize.
   ui::AXTreeUpdate out_update2;
   ax_serializer.SerializeChanges(textfield_wrapper, &out_update2);
 
   size_t node_count = out_update2.nodes.size();
 
   // We should have far more updates this time around.
   ASSERT_GE(node_count, 10U);
 
   int text_field_update_index = -1;
   for (size_t i = 0; i < node_count; ++i) {
     if (textfield_wrapper->GetID() == out_update2.nodes[i].id)
       text_field_update_index = i;
   }
 
   ASSERT_NE(-1, text_field_update_index);
   ASSERT_EQ(ui::AX_ROLE_TEXT_FIELD,
             out_update2.nodes[text_field_update_index].role);
 }