Implement windows mousewheel scroll by page functionality

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 6150165f7eb254e287167fc3336852a003a978e2..93815b05aa4b5c49782be7ec108fe9d0484d7e6f 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -2556,14 +2556,12 @@ bool RenderViewImpl::isPointerLocked() {
 
 void RenderViewImpl::didActivateCompositor(int input_handler_identifier) {
 #if !defined(OS_MACOSX)  // many events are unhandled - http://crbug.com/138003
-#if !defined(OS_WIN)  // http://crbug.com/160122
   InputHandlerManager* input_handler_manager =
       RenderThreadImpl::current()->input_handler_manager();
   if (input_handler_manager)
     input_handler_manager->AddInputHandler(
         routing_id_, input_handler_identifier, AsWeakPtr());
 #endif
-#endif
 
   RenderWidget::didActivateCompositor(input_handler_identifier);