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

ui/views/win/hwnd_message_handler.h

Index: ui/views/win/hwnd_message_handler.h
===================================================================
--- ui/views/win/hwnd_message_handler.h	(revision 245191)
+++ ui/views/win/hwnd_message_handler.h	(working copy)
@@ -542,9 +542,12 @@
   // 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);
 };