Implement AutomationNode.querySelector().

extensions/renderer/api/automation/automation_api_helper.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 "extensions/renderer/api/automation/automation_api_helper.h"
+
+#include <string>
+
+#include "content/public/renderer/render_view.h"
+#include "extensions/common/extension_messages.h"
+#include "third_party/WebKit/public/web/WebAXObject.h"
+#include "third_party/WebKit/public/web/WebDocument.h"
+#include "third_party/WebKit/public/web/WebElement.h"
+#include "third_party/WebKit/public/web/WebExceptionCode.h"
+#include "third_party/WebKit/public/web/WebFrame.h"
+#include "third_party/WebKit/public/web/WebNode.h"
+#include "third_party/WebKit/public/web/WebView.h"
+
+namespace extensions {
+
+AutomationApiHelper::AutomationApiHelper(content::RenderView* render_view)
+    : content::RenderViewObserver(render_view) {
+}
+
+AutomationApiHelper::~AutomationApiHelper() {
+}
+
+bool AutomationApiHelper::OnMessageReceived(const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(AutomationApiHelper, message)
+    IPC_MESSAGE_HANDLER(ExtensionMsg_AutomationQuerySelector, OnQuerySelector)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void AutomationApiHelper::OnQuerySelector(int acc_obj_id,
+                                          int request_id,
+                                          const base::string16& selector) {
+  if (!render_view() || !render_view()->GetWebView() ||
+      !render_view()->GetWebView()->mainFrame()) {
+    LOG(WARNING) << "No main frame";
+    // TODO(aboxhall): return error result
+  }
+  blink::WebDocument document =
+      render_view()->GetWebView()->mainFrame()->document();
+  if (document.isNull()) {
+    LOG(WARNING) << "Document is null";
+    // TODO(aboxhall): return error result
+  }
+  blink::WebNode node = document;
+  if (acc_obj_id > 0) {
+    const blink::WebAXObject& obj =
+        document.accessibilityObjectFromID(acc_obj_id);
+    node = obj.node();

[dmazzoni, 2014/10/29 00:00:10]

One subtle nuance here - not every AXObject corresponds to a node - it's
possible that an AXObject is CSS generated content, an anonymous render block,
or a scroll view, or a spinner button, or one of many objects that aren't nodes.

You should check for a null node here - but also consider that it might be
confusing if this query fails on some ax objects but succeeds on others - maybe
walk up the ancestors and run the query on the nearest ancestor that corresponds
to a node?

[aboxhall, 2014/10/30 18:36:44]

PTAL - I've tried to address this.

+  }
+  blink::WebString web_selector(selector);
+  blink::WebExceptionCode ec = 0;
+  blink::WebElement result = node.querySelector(web_selector, ec);
+  int result_acc_obj_id = 0;
+  if (!ec && !result.isNull()) {
+    blink::WebAXObject ax_obj = document.accessibilityObjectFromNode(result);
+    result_acc_obj_id = ax_obj.axID();

[dmazzoni, 2014/10/27 18:47:36]

Need to check if ax_obj is valid - the best way is to call isDetached(), which
tells you if it's NULL (i.e. it was never assigned to anything), or if it's
detached (meaning it used to point to something, but the object it pointed to is
now NULL, and it only exists until all references to it go away).

[aboxhall, 2014/10/28 23:43:57]

Done.

+  }
+  Send(new ExtensionHostMsg_AutomationQuerySelector_Result(
+      routing_id(), request_id, "", result_acc_obj_id));
+}
+
+}  // namespace extensions