Support bottom-right anchored fixed-position elements during a pinch gesture

cc/layers/layer_position_constraint.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 CC_LAYER_POSITION_CONSTRAINT_H_
+#define CC_LAYER_POSITION_CONSTRAINT_H_
+
+#include "cc/base/cc_export.h"
+
+namespace cc {
+
+class CC_EXPORT LayerPositionConstraint {
+ public:
+  LayerPositionConstraint();
+
+  void set_is_fixed_position(bool fixed) { is_fixed_position_ = fixed; }
+  bool is_fixed_position() const { return is_fixed_position_; }
+  void set_is_fixed_to_right_edge(bool fixed) {
+    is_fixed_to_right_edge_ = fixed;
+  }
+  bool is_fixed_to_right_edge() const { return is_fixed_to_right_edge_; }
+  void set_is_fixed_to_bottom_edge(bool fixed) {
+    is_fixed_to_bottom_edge_ = fixed;
+  }
+  bool is_fixed_to_bottom_edge() const { return is_fixed_to_bottom_edge_; }
+
+  bool operator==(const LayerPositionConstraint&) const;
+  bool operator!=(const LayerPositionConstraint&) const;
+
+ private:
+  bool is_fixed_position_       : 1;
+  bool is_fixed_to_right_edge_  : 1;
+  bool is_fixed_to_bottom_edge_ : 1;
+};
+
+}  // namespace cc
+
+#endif  // CC_LAYER_POSITION_CONSTRAINT_H_