[SimpleCache] Prefetch stream 1 so that the first read is faster

net/disk_cache/simple/simple_synchronous_entry.h

Index: net/disk_cache/simple/simple_synchronous_entry.h
diff --git a/net/disk_cache/simple/simple_synchronous_entry.h b/net/disk_cache/simple/simple_synchronous_entry.h
index a7e6e66b12091847ed31623ecdebf1b41d008acc..b2dd40a386ad7eaa3b05725c17a906244913d633 100644
--- a/net/disk_cache/simple/simple_synchronous_entry.h
+++ b/net/disk_cache/simple/simple_synchronous_entry.h
@@ -79,6 +79,7 @@ struct SimpleEntryCreationResults {
 
   SimpleSynchronousEntry* sync_entry;
   scoped_refptr<net::GrowableIOBuffer> stream_0_data;
+  scoped_refptr<net::GrowableIOBuffer> stream_1_prefetch_data;
   SimpleEntryStat entry_stat;
   uint32_t stream_0_crc32;
   int result;
@@ -280,9 +281,11 @@ class SimpleSynchronousEntry {
   bool CheckHeaderAndKey(int file_index);
 
   // Returns a net error, i.e. net::OK on success.
-  int InitializeForOpen(SimpleEntryStat* out_entry_stat,
-                        scoped_refptr<net::GrowableIOBuffer>* stream_0_data,
-                        uint32_t* out_stream_0_crc32);
+  int InitializeForOpen(
+      SimpleEntryStat* out_entry_stat,
+      scoped_refptr<net::GrowableIOBuffer>* stream_0_data,
+      uint32_t* out_stream_0_crc32,
+      scoped_refptr<net::GrowableIOBuffer>* stream_1_prefetch_data);
 
   // Writes the header and key to a newly-created stream file. |index| is the
   // index of the stream. Returns true on success; returns false and sets