Inform disk cache of WebKit memory cache hits.

net/disk_cache/in_flight_backend_io.h

Index: net/disk_cache/in_flight_backend_io.h
diff --git a/net/disk_cache/in_flight_backend_io.h b/net/disk_cache/in_flight_backend_io.h
index 659a33af15ff352b3b01330b77902ad69b82afb2..09ee323a073bf0925b91c6ba54ab0c7e9dfbec22 100644
--- a/net/disk_cache/in_flight_backend_io.h
+++ b/net/disk_cache/in_flight_backend_io.h
@@ -70,6 +70,7 @@ class BackendIO : public BackgroundIO {
   void GetAvailableRange(EntryImpl* entry, int64 offset, int len, int64* start);
   void CancelSparseIO(EntryImpl* entry);
   void ReadyForSparseIO(EntryImpl* entry);
+  void UpdateRankForExternalCacheHit(EntryImpl* entry);
 
  private:
   // There are two types of operations to proxy: regular backend operations are
@@ -100,7 +101,8 @@ class BackendIO : public BackgroundIO {
     OP_WRITE_SPARSE,
     OP_GET_RANGE,
     OP_CANCEL_IO,
-    OP_IS_READY
+    OP_IS_READY,
+    OP_UPDATE_RANK,
   };
 
   virtual ~BackendIO();
@@ -175,6 +177,7 @@ class InFlightBackendIO : public InFlightIO {
                          net::CompletionCallback* callback);
   void CancelSparseIO(EntryImpl* entry);
   void ReadyForSparseIO(EntryImpl* entry, net::CompletionCallback* callback);
+  void UpdateRankForExternalCacheHit(EntryImpl* entry);
 
   // Blocks until all operations are cancelled or completed.
   void WaitForPendingIO();