Relanding this as this caused layout tests failures on Win7 due to the call to ShowScrollBars being…

ui/views/win/hwnd_message_handler.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 UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 #define UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 
 #include <windows.h>
 #include <atlbase.h>
 #include <atlapp.h>
@@ skipping 524 matching lines @@
 
   // If > 0 indicates a menu is running (we're showing a native menu).
   int menu_depth_;
 
   // A factory used to lookup appbar autohide edges.
   base::WeakPtrFactory<HWNDMessageHandler> autohide_factory_;
 
   // Generates touch-ids for touch-events.
   ui::SequentialIDGenerator id_generator_;
 
-  // Indicates if the window has the WS_VSCROLL and WS_HSCROLL styles set.
-  bool scroll_styles_set_;
+  // Indicates if the window needs the WS_VSCROLL and WS_HSCROLL styles.
+  bool needs_scroll_styles_;
+
+  // Set to true if we are in the context of a sizing or moving operation.
+  bool in_size_move_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(HWNDMessageHandler);
 };
 
 // This window property if set on the window does not activate the window for a
 // touch based WM_MOUSEACTIVATE message.
 const wchar_t kIgnoreTouchMouseActivateForWindow[] =
     L"Chrome.IgnoreMouseActivate";
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_