Mac: Add rails for scrolling.

content/browser/renderer_host/render_widget_host_view_mac.mm

 // 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/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 2237 matching lines @@
   if ([event phase] != NSEventPhaseEnded &&
       [event phase] != NSEventPhaseCancelled) {
     return;
   }
 
   if (renderWidgetHostView_->render_widget_host_) {
     // History-swiping is not possible if the logic reaches this point.
     // Allow rubber-banding in both directions.
     bool canRubberbandLeft = true;
     bool canRubberbandRight = true;
-    const WebMouseWheelEvent webEvent = WebInputEventFactory::mouseWheelEvent(
+    WebMouseWheelEvent webEvent = WebInputEventFactory::mouseWheelEvent(
         event, self, canRubberbandLeft, canRubberbandRight);
+    webEvent.railsMode = mouseWheelFilter_.UpdateRailsMode(webEvent);
     renderWidgetHostView_->render_widget_host_->ForwardWheelEvent(webEvent);
   }
 
   if (endWheelMonitor_) {
     [NSEvent removeMonitor:endWheelMonitor_];
     endWheelMonitor_ = nil;
   }
 }
 
 - (void)beginGestureWithEvent:(NSEvent*)event {
@@ skipping 101 matching lines @@
       handler:^(NSEvent* blockEvent) {
           [self shortCircuitScrollWheelEvent:blockEvent];
           return blockEvent;
       }];
   }
 
   // This is responsible for content scrolling!
   if (renderWidgetHostView_->render_widget_host_) {
     BOOL canRubberbandLeft = [responderDelegate_ canRubberbandLeft:self];
     BOOL canRubberbandRight = [responderDelegate_ canRubberbandRight:self];
-    const WebMouseWheelEvent webEvent = WebInputEventFactory::mouseWheelEvent(
+    WebMouseWheelEvent webEvent = WebInputEventFactory::mouseWheelEvent(
         event, self, canRubberbandLeft, canRubberbandRight);
+    webEvent.railsMode = mouseWheelFilter_.UpdateRailsMode(webEvent);
     renderWidgetHostView_->render_widget_host_->ForwardWheelEvent(webEvent);
   }
 }
 
 // Called repeatedly during a pinch gesture, with incremental change values.
 - (void)magnifyWithEvent:(NSEvent*)event {
   if (!renderWidgetHostView_->render_widget_host_)
     return;
 
   // If, due to nesting of multiple gestures (e.g, from multiple touch
@@ skipping 1057 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end