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 <atlwin.h>
+#include <atlcrack.h>
+#include <oleacc.h>
+
+#include "base/basictypes.h"
+#include "base/win/scoped_comptr.h"
+#include "content/common/content_export.h"
+#include "ui/gfx/rect.h"
+
+namespace content {
+class BrowserAccessibilityManagerWin;
+
+// Reasons for the existence of this class outlined below:-
+// 1. Some screen readers expect every tab / every unique web content container
+//    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.
+// 2. There are legacy drivers for trackpads/trackpoints which have special
+//    code for sending mouse wheel and scroll events to the
+//    Chrome_RenderWidgetHostHWND window.
+// 3. Windowless NPAPI plugins like Flash and Silverlight which expect the
+//    container window to have the same bounds as the web page. In Aura, the
+//    default container window is the whole window which includes the web page
+//    TabContents, etc. This causes the plugin mouse event calculations to

[sky, 2014/02/05 15:22:44]

nit: TabContents->WebContents.

[ananta, 2014/02/05 16:35:51]

Done.

+//    fail.
+//    We should look to get rid of this code when all of the above are fixed.
+
+// 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:
+  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();
+
+  // Functions to show and hide the window.
+  void Show();
+  void Hide();
+
+  // Resizes the window to the bounds passed in.
+  void SetBounds(const gfx::Rect& bounds);
+
+  // Destroys the window, which in turn deletes the instance of this class.
+  void Destroy();
+
+ 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_
+