Use the previews black list for offline previews

components/previews/core/previews_decider.h

+// 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 COMPONENTS_PREVIEWS_CORE_PREVIEWS_DECIDER_H_
+#define COMPONENTS_PREVIEWS_CORE_PREVIEWS_DECIDER_H_
+
+#include "components/previews/core/previews_opt_out_store.h"
+
+namespace net {
+class URLRequest;
+}
+
+namespace previews {
+
+class PreviewsDecider {
+ public:
+  // Whether |request| is allowed to show a preview of |type|.
+  virtual bool ShouldAllowPreview(const net::URLRequest& request,
+                                  PreviewsType type) const = 0;
+
+ protected:
+  PreviewsDecider() {}
+  virtual ~PreviewsDecider() {}
+};
+
+}  // namespace previews
+
+#endif  // COMPONENTS_PREVIEWS_CORE_PREVIEWS_DECIDER_H_