content: Cleanup class/struct forward declarations

content/browser/accessibility/accessibility_tree_formatter.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_TREE_FORMATTER_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_TREE_FORMATTER_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "content/browser/accessibility/browser_accessibility.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
-class WebContents;
-
 // A utility class for formatting platform-specific accessibility information,
 // for use in testing, debugging, and developer tools.
 // This is extended by a subclass for each platform where accessibility is
 // implemented.
 class CONTENT_EXPORT AccessibilityTreeFormatter {
  public:
   explicit AccessibilityTreeFormatter();
   virtual ~AccessibilityTreeFormatter();
 
   // A single filter specification. See GetAllowString() and GetDenyString()
@@ skipping 131 matching lines @@
 
   // Whether or not node ids should be included in the dump.
   bool show_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(AccessibilityTreeFormatter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_ACCESSIBILITY_TREE_FORMATTER_H_