Fix mouse wheel scrolling on PDFs.

content/browser/renderer_host/input/mouse_wheel_event_queue.cc

 // Copyright 2016 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/input/mouse_wheel_event_queue.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
 #include "base/trace_event/trace_event.h"
 
@@ skipping 209 matching lines @@
 
 void MouseWheelEventQueue::TryForwardNextEventToRenderer() {
   TRACE_EVENT0("input", "MouseWheelEventQueue::TryForwardNextEventToRenderer");
 
   if (wheel_queue_.empty() || event_sent_for_gesture_ack_)
     return;
 
   event_sent_for_gesture_ack_.reset(wheel_queue_.front());
   wheel_queue_.pop_front();
 
-  MouseWheelEventWithLatencyInfo send_event(*event_sent_for_gesture_ack_);
-  if (send_gestures_)
-    send_event.event.canScroll = false;
-
-  client_->SendMouseWheelEventImmediately(send_event);
+  client_->SendMouseWheelEventImmediately(*event_sent_for_gesture_ack_);
 }
 
 void MouseWheelEventQueue::SendScrollEnd(blink::WebGestureEvent update_event,
                                          bool synthetic) {
   DCHECK((synthetic && !needs_scroll_end_) || needs_scroll_end_);
 
   GestureEventWithLatencyInfo scroll_end(update_event);
   scroll_end.event.timeStampSeconds =
       (base::TimeTicks::Now() - base::TimeTicks()).InSecondsF();
   scroll_end.event.type = WebInputEvent::GestureScrollEnd;
@@ skipping 31 matching lines @@
   scroll_begin.event.data.scrollBegin.targetViewport = false;
   scroll_begin.event.data.scrollBegin.deltaHintUnits =
       gesture_update.event.data.scrollUpdate.deltaUnits;
 
   needs_scroll_begin_ = false;
   needs_scroll_end_ = true;
   client_->SendGestureEvent(scroll_begin);
 }
 
 }  // namespace content