cc: Move SyncedScrollOffset to scroll tree

cc/proto/synced_property_conversions.h

Index: cc/proto/synced_property_conversions.h
diff --git a/cc/proto/synced_property_conversions.h b/cc/proto/synced_property_conversions.h
new file mode 100644
index 0000000000000000000000000000000000000000..7f3c62308ead93e2c2e0fa2f07aa489b22a38858
--- /dev/null
+++ b/cc/proto/synced_property_conversions.h
@@ -0,0 +1,26 @@
+// 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.
+
+#ifndef CC_PROTO_SYNCED_PROPERTY_CONVERSIONS_H_
+#define CC_PROTO_SYNCED_PROPERTY_CONVERSIONS_H_
+
+#include "cc/base/cc_export.h"
+#include "cc/trees/property_tree.h"
+
+namespace cc {
+
+namespace proto {
+class SyncedProperty;
+}  // namespace proto
+
+CC_EXPORT void SyncedScrollOffsetToProto(
+    const SyncedScrollOffset& synced_scroll_offset,
+    proto::SyncedProperty* proto);
+CC_EXPORT void ProtoToSyncedScrollOffset(
+    const proto::SyncedProperty& proto,
+    SyncedScrollOffset* synced_scroll_offset);
+
+}  // namespace cc
+
+#endif  // CC_PROTO_SYNCED_PROPERTY_CONVERSIONS_H_