Don't disable threaded input handling if rubberbanding is disabled.

content/renderer/render_view_impl.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/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <memory>
 
@@ skipping 1946 matching lines @@
       GetRoutingID(), text_input_type != blink::WebTextInputTypeNone));
 #endif
 }
 
 void RenderViewImpl::initializeLayerTreeView() {
   RenderWidget::initializeLayerTreeView();
   RenderWidgetCompositor* rwc = compositor();
   if (!rwc)
     return;
 
-  bool use_threaded_event_handling = true;
-#if defined(OS_MACOSX)
-  // Disable threaded event handling if content is not handling the elastic
-  // overscroll effect. This includes the cases where the elastic overscroll
-  // effect is being handled by Blink (because of command line flags) and older
-  // operating system versions which do not have an elastic overscroll effect
-  // (SnowLeopard, which has Aqua scrollbars which need synchronous updates).
-  use_threaded_event_handling = compositor_deps_->IsElasticOverscrollEnabled();
-#endif
-  if (!use_threaded_event_handling)
-    return;
-
   RenderThreadImpl* render_thread = RenderThreadImpl::current();
   // render_thread may be NULL in tests.
   InputHandlerManager* input_handler_manager =
       render_thread ? render_thread->input_handler_manager() : NULL;
   if (input_handler_manager) {
     input_handler_manager->AddInputHandler(
         GetRoutingID(), rwc->GetInputHandler(), AsWeakPtr(),
         webkit_preferences_.enable_scroll_animator);
     has_added_input_handler_ = true;
   }
@@ skipping 978 matching lines @@
                             INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
   }
 
   std::unique_ptr<InputEventAck> ack(
       new InputEventAck(InputEventAckSource::MAIN_THREAD, input_event->type,
                         INPUT_EVENT_ACK_STATE_NOT_CONSUMED));
   OnInputEventAck(std::move(ack));
 }
 
 }  // namespace content