Route Scroll events through a cc::InputHandler

ui/compositor/overscroll/ui_scroll_input_manager.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 "ui/compositor/overscroll/ui_scroll_input_manager.h"
+
+#include "base/logging.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/overscroll/ui_input_handler.h"
+#include "ui/events/event.h"
+
+namespace ui {
+
+UIScrollInputManager::UIScrollInputManager(
+    const base::WeakPtr<cc::InputHandler>& input_handler)
+    : input_wrapper_(new UIInputHandler(input_handler)) {}
+
+UIScrollInputManager::~UIScrollInputManager() {}
+
+bool UIScrollInputManager::OnScrollEvent(const ScrollEvent& event,
+                                         Layer* layer_to_scroll) {
+  // Note there is no "begin". Currently it's only needed for hit testing,
+  // but UI already knows which layer should be scrolling.
+  input_wrapper_->HandleScrollUpdate(event, layer_to_scroll->GetElementId());
+  if (event.momentum_phase() == EventMomentumPhase::END)
+    input_wrapper_->HandleScrollEnd(event);
+  return true;
+}
+
+}  // namespace ui