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

net/disk_cache/mem_backend_impl.h

Index: net/disk_cache/mem_backend_impl.h
diff --git a/net/disk_cache/mem_backend_impl.h b/net/disk_cache/mem_backend_impl.h
index 85b0144b670ede7eb700740029882f300efa5bdd..abf14439db7b968251487920a04c671f51e7483e 100644
--- a/net/disk_cache/mem_backend_impl.h
+++ b/net/disk_cache/mem_backend_impl.h
@@ -66,29 +66,18 @@ class NET_EXPORT_PRIVATE MemBackendImpl : public Backend {
   virtual int32 GetEntryCount() const OVERRIDE;
   virtual int OpenEntry(const std::string& key, Entry** entry,
                         OldCompletionCallback* callback) OVERRIDE;
-  virtual int OpenEntry(const std::string& key, Entry** entry,
-                        const net::CompletionCallback& callback) OVERRIDE;
   virtual int CreateEntry(const std::string& key, Entry** entry,
                           OldCompletionCallback* callback) OVERRIDE;
-  virtual int CreateEntry(const std::string& key, Entry** entry,
-                          const net::CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntry(const std::string& key,
                         OldCompletionCallback* callback) OVERRIDE;
   virtual int DoomAllEntries(OldCompletionCallback* callback) OVERRIDE;
-  virtual int DoomAllEntries(const net::CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntriesBetween(const base::Time initial_time,
                                  const base::Time end_time,
                                  OldCompletionCallback* callback) OVERRIDE;
-  virtual int DoomEntriesBetween(
-      const base::Time initial_time,
-      const base::Time end_time,
-      const net::CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntriesSince(const base::Time initial_time,
                                OldCompletionCallback* callback) OVERRIDE;
   virtual int OpenNextEntry(void** iter, Entry** next_entry,
                             OldCompletionCallback* callback) OVERRIDE;
-  virtual int OpenNextEntry(void** iter, Entry** next_entry,
-                            const net::CompletionCallback& callback) OVERRIDE;
   virtual void EndEnumeration(void** iter) OVERRIDE;
   virtual void GetStats(
       std::vector<std::pair<std::string, std::string> >* stats) OVERRIDE {}