Start work on splitting off the usage piece of in-memory index. This revision is just from the prev…

net/http/http_cache.h

Index: net/http/http_cache.h
diff --git a/net/http/http_cache.h b/net/http/http_cache.h
index f0f2a0f417a340336153549bb0f09c721e3e622d..0285e9f0c153cf2aa37ee5302728453953fd7ceb 100644
--- a/net/http/http_cache.h
+++ b/net/http/http_cache.h
@@ -31,6 +31,7 @@
 #include "net/base/load_states.h"
 #include "net/base/net_export.h"
 #include "net/base/request_priority.h"
+#include "net/disk_cache/disk_cache.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_transaction_factory.h"
 
@@ -43,7 +44,6 @@ class ProcessMemoryDump;
 }  // namespace base
 
 namespace disk_cache {
-class Backend;
 class Entry;
 }  // namespace disk_cache
 
@@ -67,6 +67,12 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory {
     DISABLE
   };
 
+  enum MemoryEntryDataHints {
+    HINT_ZERO_LIFETIME = 1,
+    HINT_RESPONSE_CANT_CONDITIONALIZE = 2,
+    HINT_UNUSED_SINCE_PREFETCH = 4
+  };
+
   // A BackendFactory creates a backend object to be used by the HttpCache.
   class NET_EXPORT BackendFactory {
    public:
@@ -378,7 +384,10 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory {
 
   // Opens the disk cache entry associated with |key|, returning an ActiveEntry
   // in |*entry|. |trans| will be notified via its IO callback if this method
-  // returns ERR_IO_PENDING.
+  // returns ERR_IO_PENDING. If there is no transaction already available,
+  // it will first check with |trans->MaybeRejectBasedOnEntryInMemoryData|,
+  // returning ERR_CACHE_ENTRY_NOT_SUITABLE after dooming the key if that
+  // rejects the entry.
   int OpenEntry(const std::string& key, ActiveEntry** entry,
                 Transaction* trans);