Revert r9953 since it caused regressions like:

chrome/views/widget_win.h

Index: chrome/views/widget_win.h
===================================================================
--- chrome/views/widget_win.h	(revision 10904)
+++ chrome/views/widget_win.h	(working copy)
@@ -486,10 +486,7 @@
   // Actually handle mouse events. These functions are called by subclasses who
   // override the message handlers above to do the actual real work of handling
   // the event in the View system.
-  bool ProcessMousePressed(const CPoint& point,
-                           UINT flags,
-                           bool dbl_click,
-                           bool non_client);
+  bool ProcessMousePressed(const CPoint& point, UINT flags, bool dbl_click);
   void ProcessMouseDragged(const CPoint& point, UINT flags);
   void ProcessMouseReleased(const CPoint& point, UINT flags);
   void ProcessMouseMoved(const CPoint& point, UINT flags, bool is_nonclient);