Suppress pause-and-buffer behavior when the HTTP response won't satisfy future requests via cache.

webkit/media/cache_util.h

+// Copyright (c) 2012 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 WEBKIT_MEDIA_CACHE_UTIL_H_
+#define WEBKIT_MEDIA_CACHE_UTIL_H_
+
+#include <vector>
+
+namespace WebKit {
+class WebURLResponse;
+}
+
+namespace webkit_media {
+
+// Reasons that a cached WebURLResponse will *not* prevent a future request to
+// the server.  Reported via UMA, so don't change/reuse previously-existing
+// values.
+enum UncacheableReason {
+  kNoData = 1 << 0,  // Not 200 or 206.
+  kPre11PartialResponse = 1 << 1,  // 206 but HTTP version < 1.1.
+  kNoStrongValidatorOnPartialResponse = 1 << 2,  // 206, no strong validator.
+  kShortMaxAge = 1 << 3,  // Max age less than 1h (arbitrary value).
+  kExpiresTooSoon = 1 << 4,  // Expires in less than 1h (arbitrary value).
+  kHasMustRevalidate = 1 << 5,  // Response asks for revalidation.
+  kNoCache = 1 << 6,  // Response included a no-cache header.
+  kNoStore = 1 << 7,  // Response included a no-store header.
+  kMaxReason  // Needs to be one more than max legitimate reason.
+};
+
+// Return the reasons "response" cannot be used for a future request (using the
+// disk cache), or an empty vector if it might be useful.
+std::vector<UncacheableReason> GetReasonsForUncacheability(
+    const WebKit::WebURLResponse& response);
+
+}  // namespace webkit_media
+
+#endif  // WEBKIT_MEDIA_CACHE_UTIL_H_