Introduce WebCachePolicy to merge cache policy enums

third_party/WebKit/public/platform/WebCachePolicy.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 WebCachePolicy_h
+#define WebCachePolicy_h
+
+namespace blink {
+
+enum class WebCachePolicy {
+    UseProtocolCachePolicy, // normal load
+    ValidatingCacheData, // reload
+    BypassingCache, // end-to-end reload
+    ReturnCacheDataElseLoad, // back/forward or encoding change - allow stale data
+    ReturnCacheDataDontLoad, // results of a post - allow stale data and only use cache
+};
+
+} // namespace blink
+
+#endif // WebCachePolicy_h