Add some simple HTMLViewer apptests.

mojo/services/html_viewer/ax_provider_impl.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 "mojo/services/html_viewer/ax_provider_impl.h"
 
 #include "mojo/services/html_viewer/blink_basic_type_converters.h"
 #include "third_party/WebKit/public/platform/WebURL.h"
 #include "third_party/WebKit/public/web/WebAXObject.h"
 #include "third_party/WebKit/public/web/WebSettings.h"
@@ skipping 10 matching lines @@
 namespace html_viewer {
 
 AxProviderImpl::AxProviderImpl(WebView* web_view) : web_view_(web_view) {
 }
 
 void AxProviderImpl::GetTree(
     const mojo::Callback<void(Array<AxNodePtr> nodes)>& callback) {
   web_view_->settings()->setAccessibilityEnabled(true);
   web_view_->settings()->setInlineTextBoxAccessibilityEnabled(true);
 
-  Array<AxNodePtr> result;
-  Populate(web_view_->accessibilityObject(), 0, 0, &result);
-  callback.Run(result.Pass());
+  // TODO(msw): Is this a deep copy?
+  WebAXObject web_ax_object = web_view_->accessibilityObject();
+  DCHECK(!web_ax_object.isDetached());
+  if (web_ax_object.updateLayoutAndCheckValidity()) {
+    Array<AxNodePtr> result;
+    Populate(web_ax_object, 0, 0, &result);
+    callback.Run(result.Pass());
+  }
 }
 
 int AxProviderImpl::Populate(const WebAXObject& ax_object,
                              int parent_id,
                              int next_sibling_id,
                              Array<AxNodePtr>* result) {
   AxNodePtr ax_node(ConvertAxNode(ax_object, parent_id, next_sibling_id));
   int ax_node_id = ax_node->id;
   if (ax_node.is_null())
     return 0;
@@ skipping 33 matching lines @@
   } else if (ax_object.childCount() == 0 &&
              !ax_object.stringValue().isEmpty()) {
     result->text = mojo::AxText::New();
     result->text->content = String::From(ax_object.stringValue());
   }
 
   return result.Pass();
 }
 
 }  // namespace html_viewer