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

content/browser/renderer_host/render_widget_host_view_aura.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_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 49 matching lines @@
 }
 
 namespace ui {
 class CompositorLock;
 class InputMethod;
 class LocatedEvent;
 class Texture;
 }
 
 namespace content {
+#if defined(OS_WIN)
+class LegacyRenderWidgetHostHWND;
+#endif
+
 class RenderWidgetHostImpl;
 class RenderWidgetHostView;
 class ResizeLock;
 
 // RenderWidgetHostView class hierarchy described in render_widget_host_view.h.
 class CONTENT_EXPORT RenderWidgetHostViewAura
     : public RenderWidgetHostViewBase,
       public ui::CompositorObserver,
       public ui::TextInputClient,
       public gfx::DisplayObserver,
@@ skipping 713 matching lines @@
     unsigned frame_id;
   };
   scoped_ptr<ReleasedFrameInfo> released_software_frame_;
   scoped_ptr<DelegatedFrameEvictor> delegated_frame_evictor_;
 
   scoped_ptr<aura::client::ScopedTooltipDisabler> tooltip_disabler_;
 
   base::WeakPtrFactory<RenderWidgetHostViewAura> weak_ptr_factory_;
 
 #if defined(OS_WIN)
-  // The dummy HWND which corresponds to the bounds of the web page. This is
-  // passed to windowless plugins like Flash/Silverlight, etc as the
-  // container window.
-  HWND plugin_parent_window_;
+  // The LegacyRenderWidgetHostHWND class provides a dummy HWND which is used
+  // for accessibility, as the container for windowless plugins like
+  // Flash/Silverlight, etc and for legacy drivers for trackpoints/trackpads,
+  // etc.
+  // This instance is deleted when the parent window is destroyed.
+  content::LegacyRenderWidgetHostHWND* legacy_render_widget_host_HWND_;

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

What are the advantages of wiring LegacyRenderWidgetHostHWND at RWHVA instead of
WebContentsViewAura?

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

RWHVA has plumbing code to track when its aura::Window is added to the
RootWindow, which is used to reparent the container HWND as needed. This is
needed for plugins to work correctly. 

 #endif
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_