Implement windows mousewheel scroll by page functionality

content/renderer/render_view_impl.cc

 // 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.
 
 #include "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/auto_reset.h"
@@ skipping 2538 matching lines @@
   mouse_lock_dispatcher_->UnlockMouse(webwidget_mouse_lock_target_.get());
 }
 
 bool RenderViewImpl::isPointerLocked() {
   return mouse_lock_dispatcher_->IsMouseLockedTo(
       webwidget_mouse_lock_target_.get());
 }
 
 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);
 
   FOR_EACH_OBSERVER(RenderViewObserver, observers_,
                     DidActivateCompositor(input_handler_identifier));
 }
 
 void RenderViewImpl::didHandleGestureEvent(
     const WebGestureEvent& event,
     bool event_cancelled) {
@@ skipping 3942 matching lines @@
   TransportDIB* dib = TransportDIB::CreateWithHandle(dib_handle);
   RenderProcess::current()->ReleaseTransportDIB(dib);
 }
 
 void RenderViewImpl::DidCommitCompositorFrame() {
   RenderWidget::DidCommitCompositorFrame();
   FOR_EACH_OBSERVER(RenderViewObserver, observers_, DidCommitCompositorFrame());
 }
 
 }  // namespace content