Revert of Remove enable/disable wheel gestures setting.

content/browser/renderer_host/overscroll_controller.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/browser/renderer_host/overscroll_controller.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
+#include "content/common/input/input_event_utils.h"
 #include "content/public/browser/overscroll_configuration.h"
 #include "content/public/common/content_switches.h"
 
 using blink::WebInputEvent;
 
 namespace {
 
 bool IsScrollEndEffectEnabled() {
   return base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
       switches::kScrollEndEffect) == "1";
 }
 
 bool IsGestureEventFromTouchpad(const blink::WebInputEvent& event) {
   DCHECK(blink::WebInputEvent::isGestureEventType(event.type));
   const blink::WebGestureEvent& gesture =
       static_cast<const blink::WebGestureEvent&>(event);
   return gesture.sourceDevice == blink::WebGestureDeviceTouchpad;
 }
 
 }  // namespace
 
 namespace content {
 
 OverscrollController::OverscrollController()
     : overscroll_mode_(OVERSCROLL_NONE),
       scroll_state_(STATE_UNKNOWN),
       overscroll_delta_x_(0.f),
       overscroll_delta_y_(0.f),
-      delegate_(NULL) {}
+      delegate_(NULL),
+      use_gesture_wheel_scrolling_(UseGestureBasedWheelScrolling()) {}
 
 OverscrollController::~OverscrollController() {
 }
 
 bool OverscrollController::ShouldProcessEvent(
     const blink::WebInputEvent& event) {
+  if (use_gesture_wheel_scrolling_) {
     switch (event.type) {
       case blink::WebInputEvent::MouseWheel:
         return false;
       case blink::WebInputEvent::GestureScrollBegin:
       case blink::WebInputEvent::GestureScrollUpdate:
       case blink::WebInputEvent::GestureScrollEnd: {
         const blink::WebGestureEvent& gesture =
             static_cast<const blink::WebGestureEvent&>(event);
         if (gesture.sourceDevice == blink::WebGestureDeviceTouchpad)
           return true;
@@ skipping 11 matching lines @@
           default:
             scrollUnits = blink::WebGestureEvent::Pixels;
             break;
         }
 
         return scrollUnits == blink::WebGestureEvent::PrecisePixels;
       }
       default:
         break;
     }
+  }
   return true;
 }
 
 bool OverscrollController::WillHandleEvent(const blink::WebInputEvent& event) {
   if (!ShouldProcessEvent(event))
     return false;
 
   bool reset_scroll_state = false;
   if (scroll_state_ != STATE_UNKNOWN ||
       overscroll_delta_x_ || overscroll_delta_y_) {
@@ skipping 334 matching lines @@
   overscroll_mode_ = mode;
   if (overscroll_mode_ == OVERSCROLL_NONE)
     overscroll_delta_x_ = overscroll_delta_y_ = 0.f;
   else
     scroll_state_ = STATE_OVERSCROLLING;
   if (delegate_)
     delegate_->OnOverscrollModeChange(old_mode, overscroll_mode_);
 }
 
 }  // namespace content