Implement CSS: scroll-boundary-behavior

cc/input/scroll_boundary_behavior.h

Index: cc/input/scroll_boundary_behavior.h
diff --git a/cc/input/scroll_boundary_behavior.h b/cc/input/scroll_boundary_behavior.h
new file mode 100644
index 0000000000000000000000000000000000000000..afdb1381e108d4164a38fe3877dad5e3d9ad9387
--- /dev/null
+++ b/cc/input/scroll_boundary_behavior.h
@@ -0,0 +1,40 @@
+// 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 CC_INPUT_SCROLL_BOUNDARY_BEHAVIOR_H_
+#define CC_INPUT_SCROLL_BOUNDARY_BEHAVIOR_H_
+
+#include "cc/cc_export.h"
+
+namespace cc {
+
+struct CC_EXPORT ScrollBoundaryBehavior {
+  enum ScrollBoundaryBehaviorType {
+    kScrollBoundaryBehaviorTypeAuto = 0x0,

[bokan, 2017/05/19 19:35:57]

You can leave the values off since they're the defaults.

[sunyunjia, 2017/05/25 20:07:10]

Done.

+    kScrollBoundaryBehaviorTypeContain = 0x1,
+    kScrollBoundaryBehaviorTypeNone = 0x2
+  };
+
+  ScrollBoundaryBehavior()
+      : x(kScrollBoundaryBehaviorTypeAuto),
+        y(kScrollBoundaryBehaviorTypeAuto) {}
+  ScrollBoundaryBehavior(ScrollBoundaryBehaviorType type) : x(type), y(type) {}

[bokan, 2017/05/19 19:35:57]

Make this explicit.

[sunyunjia, 2017/05/25 20:07:10]

Done.

+  ScrollBoundaryBehavior(ScrollBoundaryBehaviorType x_type,
+                         ScrollBoundaryBehaviorType y_type)
+      : x(x_type), y(y_type) {}
+
+  ScrollBoundaryBehaviorType x;
+  ScrollBoundaryBehaviorType y;
+
+  bool operator==(const ScrollBoundaryBehavior& a) const {
+    return (a.x == x) && (a.y == y);
+  }
+  bool operator!=(const ScrollBoundaryBehavior& a) const {
+    return (a.x != x) || (a.y != y);

[bokan, 2017/05/19 19:35:57]

You can reuse operator==: return !(*this == a)

[sunyunjia, 2017/05/25 20:07:10]

Done.

+  }
+};
+
+}  // namespace cc
+
+#endif  // CC_INPUT_SCROLL_BOUNDARY_BEHAVIOR_H_