Implement in-memory byte hints in SimpleCache

net/disk_cache/simple/simple_index_file.h

Index: net/disk_cache/simple/simple_index_file.h
diff --git a/net/disk_cache/simple/simple_index_file.h b/net/disk_cache/simple/simple_index_file.h
index 9e119d584aea12f1af0547d25f25706795f64548..3946e2e245227d13113bf2c2cd39c88427d3eb59 100644
--- a/net/disk_cache/simple/simple_index_file.h
+++ b/net/disk_cache/simple/simple_index_file.h
@@ -67,12 +67,15 @@ class NET_EXPORT_PRIVATE SimpleIndexFile {
 
     SimpleIndex::IndexWriteToDiskReason reason() const { return reason_; }
     uint64_t entry_count() const { return entry_count_; }
+    bool has_entry_in_memory_data() const { return version_ >= 8; }
 
    private:
     FRIEND_TEST_ALL_PREFIXES(IndexMetadataTest, Basics);
     FRIEND_TEST_ALL_PREFIXES(IndexMetadataTest, Serialize);
     FRIEND_TEST_ALL_PREFIXES(IndexMetadataTest, ReadV6Format);
+    FRIEND_TEST_ALL_PREFIXES(SimpleIndexFileTest, ReadV7Format);
     friend class V6IndexMetadataForTest;
+    friend class V7IndexMetadataForTest;
 
     uint64_t magic_number_;
     uint32_t version_;