Fix 15 coverity complaints....

net/tools/dump_cache/dump_cache.cc

 // Copyright (c) 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.
 
 // This command-line program dumps the contents of a set of cache files, either
 // to stdout or to another set of cache files.
 
 #include <stdio.h>
 #include <string>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/process_util.h"
 #include "base/scoped_handle.h"
 #include "base/string_util.h"
 
 #include "net/disk_cache/disk_format.h"
 
 enum Errors {
   GENERIC = -1,
   ALL_GOOD = 0,
   INVALID_ARGUMENT = 1,
   FILE_ACCESS_ERROR,
   UNKNOWN_VERSION,
   TOOL_NOT_FOUND,
 };
 
-int GetMajorVersion(const std::wstring input_path);
-int DumpContents(const std::wstring input_path);
-int DumpHeaders(const std::wstring input_path);
-int RunSlave(const std::wstring input_path, const std::wstring pipe_number);
-int Upgrade(const std::wstring output_path, HANDLE pipe);
+int GetMajorVersion(const std::wstring& input_path);
+int DumpContents(const std::wstring& input_path);
+int DumpHeaders(const std::wstring& input_path);
+int RunSlave(const std::wstring& input_path, const std::wstring& pipe_number);
+int Upgrade(const std::wstring& output_path, HANDLE pipe);
 HANDLE CreateServer(std::wstring* pipe_number);
 
 const char kUpgradeHelp[] =
     "\nIn order to use the upgrade function, a version of this tool that\n"
     "understands the file format of the files to upgrade is needed. For\n"
     "instance, to upgrade files saved with file format 3.4 to version 5.2,\n"
     "a version of this program that was compiled with version 3.4 has to be\n"
     "located beside this executable, and named dump_cache_3.exe, and this\n"
     "executable should be compiled with version 5.2 being the current one.";
 
@@ skipping 17 matching lines @@
 int Help() {
   printf("warning: input files are modified by this tool\n");
   printf("dump_cache --input=path1 [--output=path2]\n");
   printf("--dump-headers: display file headers\n");
   printf("--dump-contents: display all entries\n");
   printf("--upgrade: copy contents to the output path\n");
   return INVALID_ARGUMENT;
 }
 
 // Starts a new process, to generate the files.
-int LaunchSlave(const CommandLine& command_line, const std::wstring pipe_number,
-                int version) {
+int LaunchSlave(const CommandLine& command_line,
+                const std::wstring& pipe_number, int version) {
   // TODO(port): remove this string-munging hackery.
   std::wstring hacked_command_line = command_line.command_line_string();
   const std::wstring old_exe(L"dump_cache.exe");
   size_t to_remove = hacked_command_line.find(old_exe);
   hacked_command_line.erase(to_remove, old_exe.size());
 
   std::wstring new_program = StringPrintf(L"%ls%d.exe", L"dump_cache_",
                                           version);
   hacked_command_line.insert(to_remove, new_program);
 
@@ skipping 75 matching lines @@
     Sleep(500);
     return ALL_GOOD;
   }
 
   if (command_line.HasSwitch(kDumpContents))
     return DumpContents(input_path);
   if (command_line.HasSwitch(kDumpHeaders))
     return DumpHeaders(input_path);
   return Help();
 }