Revert of Remove enable/disable wheel gestures setting.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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 "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 2502 matching lines @@
             .Contains(gfx::ToRoundedPoint(hit_test_point_in_layer_space))) {
       TRACE_EVENT0("cc",
                    "LayerImpl::tryScroll: Failed NonFastScrollableRegion");
       scroll_status.thread = InputHandler::SCROLL_ON_MAIN_THREAD;
       scroll_status.main_thread_scrolling_reasons =
           MainThreadScrollingReason::kNonFastScrollableRegion;
       return scroll_status;
     }
   }
 
+  if (IsWheelBasedScroll(type) &&
+      !active_tree()->settings().use_mouse_wheel_gestures) {
+    EventListenerProperties event_properties =
+        active_tree()->event_listener_properties(
+            EventListenerClass::kMouseWheel);
+    if (event_properties != EventListenerProperties::kNone) {
+      TRACE_EVENT0("cc", "LayerImpl::tryScroll: Failed WheelEventHandlers");
+      scroll_status.thread = InputHandler::SCROLL_ON_MAIN_THREAD;
+      scroll_status.main_thread_scrolling_reasons =
+          MainThreadScrollingReason::kEventHandlers;
+      return scroll_status;
+    }
+  }
+
   if (!scroll_node->data.scrollable) {
     TRACE_EVENT0("cc", "LayerImpl::tryScroll: Ignored not scrollable");
     scroll_status.thread = InputHandler::SCROLL_IGNORED;
     scroll_status.main_thread_scrolling_reasons =
         MainThreadScrollingReason::kNotScrollable;
     return scroll_status;
   }
 
   gfx::ScrollOffset max_scroll_offset =
       scroll_tree.MaxScrollOffset(scroll_node->id);
@@ skipping 1502 matching lines @@
     const {
   return fixed_raster_scale_attempted_scale_change_history_.count() >=
          kFixedRasterScaleAttemptedScaleChangeThreshold;
 }
 
 void LayerTreeHostImpl::SetFixedRasterScaleAttemptedToChangeScale() {
   fixed_raster_scale_attempted_scale_change_history_.set(0);
 }
 
 }  // namespace cc