Adding phase info to wheel events migrated to wheel phase handler class.

content/browser/renderer_host/input/mouse_wheel_phase_handler.h

+// Copyright (c) 2017 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 MOUSE_WHEEL_PHASE_HANDLER_H_
+#define MOUSE_WHEEL_PHASE_HANDLER_H_
+
+#include "base/timer/timer.h"
+#include "content/browser/renderer_host/render_widget_host_delegate.h"
+
+namespace content {
+class RenderWidgetHostImpl;
+class RenderWidgetHostViewBase;
+
+// The duration after which a synthetic wheel with zero deltas and
+// phase = |kPhaseEnded| will be sent after the last wheel event.
+const int64_t kDefaultMouseWheelLatchingTransactionMs = 100;
+
+class MouseWheelPhaseHandler {
+ public:
+  MouseWheelPhaseHandler(RenderWidgetHostImpl* const host,
+                         RenderWidgetHostViewBase* const host_view);
+  ~MouseWheelPhaseHandler() {}
+
+  void AddPhaseIfNeededAndScheduleEndEvent(
+      blink::WebMouseWheelEvent& mouse_wheel_event,
+      bool should_route_event);
+  void DispatchPendingWheelEndEvent();
+  void IgnorePendingWheelEndEvent();
+  bool HasPendingWheelEndEvent() const {
+    return mouse_wheel_end_dispatch_timer_.IsRunning();
+  }
+
+ private:
+  void SendSyntheticWheelEventWithPhaseEnded(
+      blink::WebMouseWheelEvent last_mouse_wheel_event,
+      bool should_route_event);
+  void ScheduleMouseWheelEndDispatching(blink::WebMouseWheelEvent wheel_event,
+                                        bool should_route_event);
+
+  RenderWidgetHostImpl* const host_;
+  RenderWidgetHostViewBase* const host_view_;
+  base::OneShotTimer mouse_wheel_end_dispatch_timer_;
+
+  DISALLOW_COPY_AND_ASSIGN(MouseWheelPhaseHandler);
+};
+
+}  // namespace content
+
+#endif  // MOUSE_WHEEL_PHASE_HANDLER_H_