First pass at adding http/backend cache to NetLog

net/disk_cache/disk_cache.h

Index: net/disk_cache/disk_cache.h
===================================================================
--- net/disk_cache/disk_cache.h	(revision 70512)
+++ net/disk_cache/disk_cache.h	(working copy)
@@ -25,6 +25,7 @@
 
 namespace net {
 class IOBuffer;
+class NetLog;
 }
 
 namespace disk_cache {
@@ -50,7 +51,8 @@
 // completes (the callback is notified).
 int CreateCacheBackend(net::CacheType type, const FilePath& path, int max_bytes,
                        bool force, base::MessageLoopProxy* thread,
-                       Backend** backend, CompletionCallback* callback);
+                       net::NetLog* net_log, Backend** backend,
+                       CompletionCallback* callback);
 
 // The root interface for a disk cache instance.
 class Backend {