Implement position: sticky updates on compositor

cc/layers/layer_sticky_position_constraint.cc

Index: cc/layers/layer_sticky_position_constraint.cc
diff --git a/cc/layers/layer_sticky_position_constraint.cc b/cc/layers/layer_sticky_position_constraint.cc
new file mode 100644
index 0000000000000000000000000000000000000000..69427ece82b0c5d655e78f76e939c88810efb533
--- /dev/null
+++ b/cc/layers/layer_sticky_position_constraint.cc
@@ -0,0 +1,55 @@
+// 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.
+
+#include "cc/layers/layer_sticky_position_constraint.h"
+
+namespace cc {
+
+LayerStickyPositionConstraint::LayerStickyPositionConstraint()
+    : is_sticky(false),
+      is_anchored_left(false),
+      is_anchored_right(false),
+      is_anchored_top(false),
+      is_anchored_bottom(false),
+      left_offset(0.f),
+      right_offset(0.f),
+      top_offset(0.f),
+      bottom_offset(0.f) {}
+
+LayerStickyPositionConstraint::LayerStickyPositionConstraint(
+    const LayerStickyPositionConstraint& other)
+    : is_sticky(other.is_sticky),
+      is_anchored_left(other.is_anchored_left),
+      is_anchored_right(other.is_anchored_right),
+      is_anchored_top(other.is_anchored_top),
+      is_anchored_bottom(other.is_anchored_bottom),
+      left_offset(other.left_offset),
+      right_offset(other.right_offset),
+      top_offset(other.top_offset),
+      bottom_offset(other.bottom_offset),
+      absolute_sticky_box_rect(other.absolute_sticky_box_rect),
+      absolute_containing_block_rect(other.absolute_containing_block_rect) {}
+
+bool LayerStickyPositionConstraint::operator==(
+    const LayerStickyPositionConstraint& other) const {
+  if (!is_sticky && !other.is_sticky)
+    return true;
+  return is_sticky == other.is_sticky &&
+         is_anchored_left == other.is_anchored_left &&
+         is_anchored_right == other.is_anchored_right &&
+         is_anchored_top == other.is_anchored_top &&
+         is_anchored_bottom == other.is_anchored_bottom &&
+         left_offset == other.left_offset &&
+         right_offset == other.right_offset && top_offset == other.top_offset &&
+         bottom_offset == other.bottom_offset &&
+         absolute_sticky_box_rect == other.absolute_sticky_box_rect &&
+         absolute_containing_block_rect == other.absolute_containing_block_rect;
+}
+
+bool LayerStickyPositionConstraint::operator!=(
+    const LayerStickyPositionConstraint& other) const {
+  return !(*this == other);
+}
+
+}  // namespace cc