Fix 15 coverity complaints....

net/tools/dump_cache/upgrade.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.
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/string_util.h"
 #include "net/base/io_buffer.h"
 #include "net/disk_cache/backend_impl.h"
 #include "net/disk_cache/entry_impl.h"
 
 namespace {
 
 const wchar_t kPipePrefix[] = L"\\\\.\\pipe\\dump_cache_";
 const int kChannelSize = 64 * 1024;
 const int kNumStreams = 4;
 
 // Simple macro to print out formatted debug messages. It is similar to a DLOG
 // except that it doesn't include a header.
 #ifdef NDEBUG
 #define DEBUGMSG(...) {}
 #else
 #define DEBUGMSG(...) { printf(__VA_ARGS__); }
 #endif
 
-HANDLE OpenServer(const std::wstring pipe_number) {
+HANDLE OpenServer(const std::wstring& pipe_number) {
   std::wstring pipe_name(kPipePrefix);
   pipe_name.append(pipe_number);
   return CreateFile(pipe_name.c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL,
                     OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
 }
 
 // This is the basic message to use between the two processes. It is intended
 // to transmit a single action (like "get the key name for entry xx"), with up
 // to 5 32-bit arguments and 4 64-bit arguments. After this structure, the rest
 // of the message has |buffer_bytes| of length with the actual data.
@@ skipping 716 matching lines @@
   pipe_name.append(*pipe_number);
 
   DWORD mode = PIPE_ACCESS_DUPLEX | FILE_FLAG_FIRST_PIPE_INSTANCE |
                FILE_FLAG_OVERLAPPED;
 
   return CreateNamedPipe(pipe_name.c_str(), mode, 0, 1, kChannelSize,
                          kChannelSize, 0, NULL);
 }
 
 // This is the controller process for an upgrade operation.
-int Upgrade(const std::wstring output_path, HANDLE pipe) {
+int Upgrade(const std::wstring& output_path, HANDLE pipe) {
   MessageLoop loop(MessageLoop::TYPE_IO);
   disk_cache::BackendImpl cache(output_path);
   if (!cache.Init()) {
     printf("Unable to initialize new files\n");
     return -1;
   }
 
   MasterSM master(&cache, pipe);
   if (!master.DoInit()) {
     printf("Unable to talk with the helper\n");
     return -1;
   }
 
   loop.Run();
   return 0;
 }
 
 // This process will only execute commands from the controller.
-int RunSlave(const std::wstring input_path, const std::wstring pipe_number) {
+int RunSlave(const std::wstring& input_path, const std::wstring& pipe_number) {
   MessageLoop loop(MessageLoop::TYPE_IO);
 
   ScopedHandle pipe(OpenServer(pipe_number));
   if (!pipe.IsValid()) {
     printf("Unable to open the server pipe\n");
     return -1;
   }
 
   disk_cache::BackendImpl cache(input_path);
   if (!cache.Init()) {
     printf("Unable to open cache files\n");
     return -1;
   }
   cache.SetUpgradeMode();
 
   SlaveSM slave(&cache, pipe);
   if (!slave.DoInit()) {
     printf("Unable to talk with the main process\n");
     return -1;
   }
 
   loop.Run();
   return 0;
 }