Don't track mouse events in HWNDMessageHandler when they are forwarded by the LegacyRenderWidgetHost

content/browser/renderer_host/legacy_render_widget_host_win.h

Index: content/browser/renderer_host/legacy_render_widget_host_win.h
===================================================================
--- content/browser/renderer_host/legacy_render_widget_host_win.h	(revision 249537)
+++ content/browser/renderer_host/legacy_render_widget_host_win.h	(working copy)
@@ -116,6 +116,12 @@
   LRESULT OnPaint(UINT message, WPARAM w_param, LPARAM l_param);
   LRESULT OnSetCursor(UINT message, WPARAM w_param, LPARAM l_param);
 
+  static LRESULT CALLBACK ParentWindowSuperClassProc(HWND window,
+                                                     UINT message,
+                                                     WPARAM w_param,
+                                                     LPARAM l_param);
+  static WNDPROC g_parent_original_class_proc;
+
   content::BrowserAccessibilityManagerWin* manager_;
   base::win::ScopedComPtr<IAccessible> window_accessible_;