Move some accessibility methods, enums and interfaces into the content/public API.

content/public/browser/accessibility_tree_formatter.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.

[jam, 2013/02/27 19:35:50]

why is this in the public api? i don't see it called from chrome

[aboxhall, 2013/02/27 21:19:59]

It isn't yet, but it will be once the chrome://accessibility page is created.

[jam, 2013/02/27 22:51:32]

you can now implement webui pages inside content (the motivation was actually
stuff like this, i.e. not to add stuff to content api just because of webui
pages). what will be in the webui page, is it just stuff inside content? if so
it should be implemented inside content. see
content_web_ui_controller_factory.cc

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_PUBLIC_BROWSER_ACCESSIBILITY_TREE_FORMATTER_H_
+#define CONTENT_PUBLIC_BROWSER_ACCESSIBILITY_TREE_FORMATTER_H_
+
+#include "base/string16.h"
+
+namespace content {
+
+class RenderViewHost;
+
+class AccessibilityTreeFormatter {
+ public:
+  virtual ~AccessibilityTreeFormatter() {}
+
+  static AccessibilityTreeFormatter* Create(RenderViewHost* rvh);
+
+  // Formats the browser accessibility tree for this render view host into
+  // a string.
+  virtual void FormatAccessibilityTree(string16* contents) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_ACCESSIBILITY_TREE_FORMATTER_H_