Reverts a commit that caused ASAN failures, and 2 dependent commits.

net/http/http_cache.h

Index: net/http/http_cache.h
diff --git a/net/http/http_cache.h b/net/http/http_cache.h
index 176d9ffe7cb8594d214ae93245782c8eb01f0c64..526da587b173002035341e0e0ab505991b9f68b4 100644
--- a/net/http/http_cache.h
+++ b/net/http/http_cache.h
@@ -157,8 +157,7 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory,
   // a network error code, and it could be ERR_IO_PENDING, in which case the
   // |callback| will be notified when the operation completes. The pointer that
   // receives the |backend| must remain valid until the operation completes.
-  int GetBackend(disk_cache::Backend** backend,
-                 const CompletionCallback& callback);
+  int GetBackend(disk_cache::Backend** backend, OldCompletionCallback* callback);
 
   // Returns the current backend (can be NULL).
   disk_cache::Backend* GetCurrentBackend() const;
@@ -191,7 +190,7 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory,
   // referred to by |url| and |http_method|.
   void OnExternalCacheHit(const GURL& url, const std::string& http_method);
 
-  // HttpTransactionFactory implementation.
+  // HttpTransactionFactory implementation:
   virtual int CreateTransaction(scoped_ptr<HttpTransaction>* trans) OVERRIDE;
   virtual HttpCache* GetCache() OVERRIDE;
   virtual HttpNetworkSession* GetSession() OVERRIDE;
@@ -244,7 +243,7 @@ class NET_EXPORT HttpCache : public HttpTransactionFactory,
   // Creates the |backend| object and notifies the |callback| when the operation
   // completes. Returns an error code.
   int CreateBackend(disk_cache::Backend** backend,
-                    const CompletionCallback& callback);
+                    OldCompletionCallback* callback);
 
   // Makes sure that the backend creation is complete before allowing the
   // provided transaction to use the object. Returns an error code.  |trans|