Changed previews component to be a layered component.

components/previews/core/previews_io_data.h

Index: components/previews/core/previews_io_data.h
diff --git a/components/previews/previews_io_data.h b/components/previews/core/previews_io_data.h
similarity index 92%
rename from components/previews/previews_io_data.h
rename to components/previews/core/previews_io_data.h
index 4017d79202984d2cbe1b5c696352a68f3add3968..16dd0099ac255834c89c1cd64eef2c6148ebb55d 100644
--- a/components/previews/previews_io_data.h
+++ b/components/previews/core/previews_io_data.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef COMPONENTS_PREVIEWS_PREVIEWS_IO_DATA_H_
-#define COMPONENTS_PREVIEWS_PREVIEWS_IO_DATA_H_
+#ifndef COMPONENTS_PREVIEWS_CORE_PREVIEWS_IO_DATA_H_
+#define COMPONENTS_PREVIEWS_CORE_PREVIEWS_IO_DATA_H_
 
 #include <string>
 
@@ -53,4 +53,4 @@ class PreviewsIOData {
 
 }  // namespace previews
 
-#endif  // COMPONENTS_PREVIEWS_PREVIEWS_IO_DATA_H_
+#endif  // COMPONENTS_PREVIEWS_CORE_PREVIEWS_IO_DATA_H_