RFC: use some in-memory state in SimpleCache to quickly cache-miss some CantConditionalize cases

net/disk_cache/simple/simple_backend_impl.cc

Index: net/disk_cache/simple/simple_backend_impl.cc
diff --git a/net/disk_cache/simple/simple_backend_impl.cc b/net/disk_cache/simple/simple_backend_impl.cc
index 88d2741e9797f8452efeea09fa1bbd376ed9354b..f9e5ffbd4bfbd9272c1550015011315808de1e3e 100644
--- a/net/disk_cache/simple/simple_backend_impl.cc
+++ b/net/disk_cache/simple/simple_backend_impl.cc
@@ -384,6 +384,14 @@ int32_t SimpleBackendImpl::GetEntryCount() const {
 int SimpleBackendImpl::OpenEntry(const std::string& key,
                                  Entry** entry,
                                  const CompletionCallback& callback) {
+  return OpenEntryWithOracleByte(key, entry, OracleCallback(), callback);
+}
+
+int SimpleBackendImpl::OpenEntryWithOracleByte(
+    const std::string& key,
+    Entry** entry,
+    const OracleCallback& oracle,
+    const CompletionCallback& callback) {
   const uint64_t entry_hash = simple_util::GetEntryHashKey(key);
 
   // TODO(gavinp): Factor out this (not quite completely) repetitive code
@@ -400,7 +408,7 @@ int SimpleBackendImpl::OpenEntry(const std::string& key,
   }
   scoped_refptr<SimpleEntryImpl> simple_entry =
       CreateOrFindActiveEntry(entry_hash, key);
-  return simple_entry->OpenEntry(entry, callback);
+  return simple_entry->OpenEntry(entry, oracle, callback);
 }
 
 int SimpleBackendImpl::CreateEntry(const std::string& key,
@@ -700,7 +708,7 @@ int SimpleBackendImpl::OpenEntryFromHash(uint64_t entry_hash,
   CompletionCallback backend_callback =
       base::Bind(&SimpleBackendImpl::OnEntryOpenedFromHash,
                  AsWeakPtr(), entry_hash, entry, simple_entry, callback);
-  return simple_entry->OpenEntry(entry, backend_callback);
+  return simple_entry->OpenEntry(entry, OracleCallback(), backend_callback);
 }
 
 int SimpleBackendImpl::DoomEntryFromHash(uint64_t entry_hash,
@@ -757,7 +765,7 @@ void SimpleBackendImpl::OnEntryOpenedFromHash(
     // finish. The entry created from hash needs to be closed, and the one
     // in |active_entries_| can be returned to the caller.
     simple_entry->Close();
-    it->second->OpenEntry(entry, callback);
+    it->second->OpenEntry(entry, OracleCallback(), callback);
   }
 }