Create a visible window with class name Chrome_RenderWidgetHostHWND which corresponds to the bounds…

content/browser/renderer_host/legacy_render_widget_host_win.h

+// Copyright (c) 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_LEGACY_RENDER_WIDGET_HOST_WIN_H_
+#define CONTENT_BROWSER_RENDERER_HOST_LEGACY_RENDER_WIDGET_HOST_WIN_H_
+
+#include <atlbase.h>
+#include <atlapp.h>

[cpu_(ooo_6.6-7.5), 2014/02/04 22:35:58]

do wee need atlapp? and atlcom ?

[ananta, 2014/02/04 23:30:45]

Changed to only include atlwin.h

+#include <atlcom.h>
+#include <atlcrack.h>
+#include <oleacc.h>
+
+#include "base/basictypes.h"
+#include "base/win/scoped_comptr.h"
+#include "content/common/content_export.h"
+
+namespace content {
+class BrowserAccessibilityManagerWin;
+
+// Some screen readers expect every tab / every unique web content container

[cpu_(ooo_6.6-7.5), 2014/02/04 22:35:58]

Please update this comment to reflect the other reason / duties of this class.
Including the plugin issue.

[ananta, 2014/02/04 23:30:45]

Done.

+// to be in its own HWND with class name Chrome_RenderWidgetHostHWND.
+// With Aura there is one main HWND which comprises the whole browser window or
+// the whole desktop. So, we need a fake HWND with the window class as
+// Chrome_RenderWidgetHostHWND as the root of the accessibility tree for each
+// tab. Additionally there are legacy drivers for trackpads/trackpoints which
+// also have special code for sending mouse wheel and scroll events to the
+// Chrome_RenderWidgetHostHWND window.
+// We should get rid of this code when the latest two versions of all
+// supported screen readers and legacy drivers no longer make this assumption.
+
+// This class implements a child HWND with the same size as the content area,
+// that delegates its accessibility implementation to the root of the
+// BrowserAccessibilityManager tree. This HWND is hooked up as the parent of
+// the root object in the BrowserAccessibilityManager tree, so when any
+// accessibility client calls ::WindowFromAccessibleObject, they get this
+// HWND instead of the DesktopWindowTreeHostWin.
+class CONTENT_EXPORT LegacyRenderWidgetHostHWND
+    : public ATL::CWindowImpl<LegacyRenderWidgetHostHWND,
+                              NON_EXPORTED_BASE(ATL::CWindow),
+                              ATL::CWinTraits<WS_CHILD> > {
+ public:
+  // Unfortunately, some screen readers trackpoint drivers look for this exact
+  //window class to enable certain features. It'd be great to remove this.

[cpu_(ooo_6.6-7.5), 2014/02/04 22:35:58]

remove comment 43/44 since we'll have a better explanation on the top.

[ananta, 2014/02/04 23:30:45]

Done.

+  DECLARE_WND_CLASS_EX(L"Chrome_RenderWidgetHostHWND", CS_DBLCLKS, 0);
+
+  explicit LegacyRenderWidgetHostHWND(HWND parent);
+  ~LegacyRenderWidgetHostHWND();
+
+  BEGIN_MSG_MAP_EX(LegacyRenderWidgetHostHWND)
+    MESSAGE_HANDLER_EX(WM_GETOBJECT, OnGetObject)
+    MESSAGE_RANGE_HANDLER(WM_KEYFIRST, WM_KEYLAST, OnKeyboardRange)
+    MESSAGE_HANDLER_EX(WM_PAINT, OnPaint)
+    MESSAGE_HANDLER_EX(WM_NCPAINT, OnNCPaint)
+    MESSAGE_HANDLER_EX(WM_ERASEBKGND, OnEraseBkGnd)
+    MESSAGE_RANGE_HANDLER(WM_MOUSEFIRST, WM_MOUSELAST, OnMouseRange)
+    MESSAGE_HANDLER_EX(WM_MOUSEACTIVATE, OnMouseActivate)
+    MESSAGE_HANDLER_EX(WM_SETCURSOR, OnSetCursor)
+    MESSAGE_HANDLER_EX(WM_TOUCH, OnTouch)
+  END_MSG_MAP()
+
+  HWND hwnd() { return m_hWnd; }
+
+  // This function handles setting the parent window if it changed, etc.
+  void SetParentWindow(HWND parent);
+
+  HWND parent() { return parent_; }
+
+  IAccessible* window_accessible() { return window_accessible_; }
+
+  void set_browser_accessibility_manager(
+      content::BrowserAccessibilityManagerWin* manager) {
+    manager_ = manager;
+  }
+
+  void OnManagerDeleted();
+
+  void Show();
+  void Hide();
+
+ protected:
+  virtual void OnFinalMessage(HWND hwnd) OVERRIDE;
+
+ private:
+  LRESULT OnEraseBkGnd(UINT message, WPARAM w_param, LPARAM l_param);
+  LRESULT OnGetObject(UINT message, WPARAM w_param, LPARAM l_param);
+  LRESULT OnKeyboardRange(UINT message, WPARAM w_param, LPARAM l_param,
+                          BOOL& handled);
+  LRESULT OnMouseRange(UINT message, WPARAM w_param, LPARAM l_param,
+                       BOOL& handled);
+  LRESULT OnMouseActivate(UINT message, WPARAM w_param, LPARAM l_param);
+  LRESULT OnTouch(UINT message, WPARAM w_param, LPARAM l_param);
+
+  LRESULT OnNCPaint(UINT message, WPARAM w_param, LPARAM l_param);
+  LRESULT OnPaint(UINT message, WPARAM w_param, LPARAM l_param);
+  LRESULT OnSetCursor(UINT message, WPARAM w_param, LPARAM l_param);
+
+  content::BrowserAccessibilityManagerWin* manager_;
+  base::win::ScopedComPtr<IAccessible> window_accessible_;
+  HWND parent_;
+
+  DISALLOW_COPY_AND_ASSIGN(LegacyRenderWidgetHostHWND);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_LEGACY_RENDER_WIDGET_HOST_WIN_H_
+