Add initial GTK web accessibility framework.

content/browser/accessibility/browser_accessibility.cc

 // 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.
 
 #include "content/browser/accessibility/browser_accessibility.h"
 
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/common/accessibility_messages.h"
 
 typedef WebAccessibility::BoolAttribute BoolAttribute;
 typedef WebAccessibility::FloatAttribute FloatAttribute;
 typedef WebAccessibility::IntAttribute IntAttribute;
 typedef WebAccessibility::StringAttribute StringAttribute;
 
-#if (defined(OS_POSIX) && !defined(OS_MACOSX)) || defined(USE_AURA)
-// There's no OS-specific implementation of BrowserAccessibilityManager
-// on Unix, so just instantiate the base class.
+#if !defined(OS_MACOSX) && \
+    !(defined(OS_WIN) && !defined(USE_AURA)) && \
+    !defined(TOOLKIT_GTK)
+// We have subclassess of BrowserAccessibility on Mac, Linux/GTK,
+// and non-Aura Win. For any other platform, instantiate the base class.
 // static
 BrowserAccessibility* BrowserAccessibility::Create() {
   return new BrowserAccessibility();
 }
 #endif
 
 BrowserAccessibility::BrowserAccessibility()
     : manager_(NULL),
       parent_(NULL),
       child_id_(0),
@@ skipping 270 matching lines @@
 
   string16 result;
   for (size_t i = 0; i < children_.size(); ++i)
     result += children_[i]->GetTextRecursive();
   return result;
 }
 
 void BrowserAccessibility::PreInitialize() {
   instance_active_ = true;
 }