Teach input_handler_proxy about once callbacks.

ui/events/blink/input_handler_proxy.h

 // Copyright 2013 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 UI_EVENTS_BLINK_INPUT_HANDLER_PROXY_H_
 #define UI_EVENTS_BLINK_INPUT_HANDLER_PROXY_H_
 
 #include <memory>
 
 #include "base/containers/hash_tables.h"
@@ skipping 53 matching lines @@
   void set_smooth_scroll_enabled(bool value) { smooth_scroll_enabled_ = value; }
 
   enum EventDisposition {
     DID_HANDLE,
     DID_NOT_HANDLE,
     DID_NOT_HANDLE_NON_BLOCKING_DUE_TO_FLING,
     DID_HANDLE_NON_BLOCKING,
     DROP_EVENT
   };
   using EventDispositionCallback =
-      base::Callback<void(EventDisposition,
-                          WebScopedInputEvent WebInputEvent,
-                          const LatencyInfo&,
-                          std::unique_ptr<ui::DidOverscrollParams>)>;
-  void HandleInputEventWithLatencyInfo(
-      WebScopedInputEvent event,
-      const LatencyInfo& latency_info,
-      const EventDispositionCallback& callback);
+      base::OnceCallback<void(EventDisposition,
+                              WebScopedInputEvent WebInputEvent,
+                              const LatencyInfo&,
+                              std::unique_ptr<ui::DidOverscrollParams>)>;
+  void HandleInputEventWithLatencyInfo(WebScopedInputEvent event,
+                                       const LatencyInfo& latency_info,
+                                       EventDispositionCallback callback);
   EventDisposition HandleInputEvent(const blink::WebInputEvent& event);
 
   // cc::InputHandlerClient implementation.
   void WillShutdown() override;
   void Animate(base::TimeTicks time) override;
   void MainThreadHasStoppedFlinging() override;
   void ReconcileElasticOverscrollAndRootScroll() override;
   void UpdateRootLayerStateForSynchronousInputHandler(
       const gfx::ScrollOffset& total_scroll_offset,
       const gfx::ScrollOffset& max_scroll_offset,
@@ skipping 168 matching lines @@
   bool has_ongoing_compositor_scroll_fling_pinch_;
 
   std::unique_ptr<base::TickClock> tick_clock_;
 
   DISALLOW_COPY_AND_ASSIGN(InputHandlerProxy);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_BLINK_INPUT_HANDLER_PROXY_H_