Remove ObserveWheelEventAndResult callbacks since they are now gesture based.

content/renderer/render_widget.h

 // 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.
 
 #ifndef CONTENT_RENDERER_RENDER_WIDGET_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 192 matching lines @@
   void RequestScheduleAnimation() override;
   void UpdateVisualState() override;
   void WillBeginCompositorFrame() override;
   void ReportFixedRasterScaleUseCounters(
       bool has_blurry_content,
       bool has_potential_performance_regression) override;
 
   // RenderWidgetInputHandlerDelegate
   void FocusChangeComplete() override;
   bool HasTouchEventHandlersAt(const gfx::Point& point) const override;
-  void ObserveWheelEventAndResult(const blink::WebMouseWheelEvent& wheel_event,
-                                  const gfx::Vector2dF& wheel_unused_delta,
-                                  bool event_processed) override;
   void ObserveGestureEventAndResult(const blink::WebGestureEvent& gesture_event,
                                     const gfx::Vector2dF& unused_delta,
                                     bool event_processed) override;
 
   void OnDidHandleKeyEvent() override;
   void OnDidOverscroll(const DidOverscrollParams& params) override;
   void OnInputEventAck(std::unique_ptr<InputEventAck> input_event_ack) override;
   void NotifyInputEventHandled(
       blink::WebInputEvent::Type handled_type) override;
   void SetInputHandler(RenderWidgetInputHandler* input_handler) override;
@@ skipping 554 matching lines @@
 
   // Indicates whether this widget has focus.
   bool has_focus_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_H_