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..1ea6f77b646f3e3676fc813c77699d5d9b383f81 100644
--- a/net/disk_cache/in_flight_backend_io.h
+++ b/net/disk_cache/in_flight_backend_io.h
@@ -55,6 +55,7 @@ class BackendIO : public BackgroundIO {
   void OpenNextEntry(void** iter, Entry** next_entry);
   void OpenPrevEntry(void** iter, Entry** prev_entry);
   void EndEnumeration(void* iterator);
+  void OnExternalCacheHit(const std::string& key);
   void CloseEntryImpl(EntryImpl* entry);
   void DoomEntryImpl(EntryImpl* entry);
   void FlushQueue();  // Dummy operation.
@@ -89,6 +90,7 @@ class BackendIO : public BackgroundIO {
     OP_OPEN_NEXT,
     OP_OPEN_PREV,
     OP_END_ENUMERATION,
+    OP_ON_EXTERNAL_CACHE_HIT,
     OP_CLOSE_ENTRY,
     OP_DOOM_ENTRY,
     OP_FLUSH_QUEUE,
@@ -159,6 +161,7 @@ class InFlightBackendIO : public InFlightIO {
   void OpenPrevEntry(void** iter, Entry** prev_entry,
                      net::CompletionCallback* callback);
   void EndEnumeration(void* iterator);
+  void OnExternalCacheHit(const std::string& key);
   void CloseEntryImpl(EntryImpl* entry);
   void DoomEntryImpl(EntryImpl* entry);
   void FlushQueue(net::CompletionCallback* callback);