Remove non-const references from MemEntryImpl.

net/disk_cache/mem_entry_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_DISK_CACHE_MEM_ENTRY_IMPL_H_
 #define NET_DISK_CACHE_MEM_ENTRY_IMPL_H_
 
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 64 matching lines @@
   }
 
   void set_prev(MemEntryImpl* prev) {
     prev_ = prev;
   }
 
   EntryType type() const {
     return parent_ ? kChildEntry : kParentEntry;
   }
 
-  std::string& key() {
-    return key_;
-  }
-
-  net::BoundNetLog& net_log() {
+  const net::BoundNetLog& net_log() {
     return net_log_;
   }
 
   // Entry interface.
   virtual void Doom() OVERRIDE;
   virtual void Close() OVERRIDE;
   virtual std::string GetKey() const OVERRIDE;
   virtual base::Time GetLastUsed() const OVERRIDE;
   virtual base::Time GetLastModified() const OVERRIDE;
   virtual int32 GetDataSize(int index) const OVERRIDE;
@@ skipping 80 matching lines @@
   bool doomed_;               // True if this entry was removed from the cache.
 
   net::BoundNetLog net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(MemEntryImpl);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_MEM_ENTRY_IMPL_H_