Fix 15 coverity complaints....

net/disk_cache/mapped_file.h

 // Copyright (c) 2006-2008 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.
 
 // See net/disk_cache/disk_cache.h for the public interface of the cache.
 
 #ifndef NET_DISK_CACHE_MAPPED_FILE_H_
 #define NET_DISK_CACHE_MAPPED_FILE_H_
 
 #include <string>
 
 #include "net/disk_cache/disk_format.h"
 #include "net/disk_cache/file.h"
 #include "net/disk_cache/file_block.h"
 
 namespace disk_cache {
 
 // This class implements a memory mapped file used to access block-files. The
 // idea is that the header and bitmap will be memory mapped all the time, and
 // the actual data for the blocks will be access asynchronously (most of the
 // time).
 class MappedFile : public File {
  public:
   MappedFile() : File(true), init_(false) {}
 
   // Performs object initialization. name is the file to use, and size is the
   // ammount of data to memory map from th efile. If size is 0, the whole file
   // will be mapped in memory.
-  void* Init(const std::wstring name, size_t size);
+  void* Init(const std::wstring& name, size_t size);
 
   void* buffer() const {
     return buffer_;
   }
 
   // Loads or stores a given block from the backing file (synchronously).
   bool Load(const FileBlock* block);
   bool Store(const FileBlock* block);
 
  protected:
   virtual ~MappedFile();
 
  private:
   bool init_;
 #if defined(OS_WIN)
   HANDLE section_;
 #endif
   void* buffer_;  // Address of the memory mapped buffer.
   size_t view_size_;  // Size of the memory pointed by buffer_.
 
   DISALLOW_COPY_AND_ASSIGN(MappedFile);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_MAPPED_FILE_H_