Arrange compositor scrolling into scroll customization format

cc/input/scroll_state.cc

+// Copyright 2015 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/input/scroll_state.h"
+
+#include "cc/layers/layer_impl.h"
+
+namespace cc {
+
+ScrollState::ScrollState(double delta_x,
+                         double delta_y,
+                         int start_position_x,
+                         int start_position_y,
+                         bool should_propagate,
+                         bool delta_consumed_for_scroll_sequence,
+                         bool is_direct_manipulation)
+    : delta_x_(delta_x),
+      delta_y_(delta_y),
+      start_position_x_(start_position_x),
+      start_position_y_(start_position_y),
+      should_propagate_(should_propagate),
+      delta_consumed_for_scroll_sequence_(delta_consumed_for_scroll_sequence),
+      is_direct_manipulation_(is_direct_manipulation),
+      caused_scroll_x_(false),
+      caused_scroll_y_(false) {}
+
+ScrollState::~ScrollState() {}
+
+void ScrollState::ConsumeDelta(double x, double y) {
+  delta_x_ -= x;
+  delta_y_ -= y;
+
+  if (x || y)
+    delta_consumed_for_scroll_sequence_ = true;
+}
+
+void ScrollState::DistributeToScrollChainDescendant() {
+  if (!scroll_chain_.empty()) {
+    LayerImpl* next = scroll_chain_.front();
+    scroll_chain_.pop_front();
+    next->DistributeScroll(this);
+  }
+}
+
+}  // namespace cc