Fix up some code not to set off coverity warnings.

net/socket/ssl_test_util.cc

 // 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.
 
 #include <string>
 #include <algorithm>
 
 #include "net/socket/ssl_test_util.h"
 
 #include "build/build_config.h"
@@ skipping 90 matching lines @@
 {
   PathService::Get(base::DIR_SOURCE_ROOT, &cert_dir_);
   cert_dir_ = cert_dir_.Append(FILE_PATH_LITERAL("net"))
                        .Append(FILE_PATH_LITERAL("data"))
                        .Append(FILE_PATH_LITERAL("ssl"))
                        .Append(FILE_PATH_LITERAL("certificates"));
 }
 
 namespace {
 
-void AppendToPythonPath(FilePath dir) {
+void AppendToPythonPath(const FilePath& dir) {
   // Do nothing if dir already on path.
 
 #if defined(OS_WIN)
   const wchar_t kPythonPath[] = L"PYTHONPATH";
   // FIXME(dkegel): handle longer PYTHONPATH variables
   wchar_t oldpath[4096];
   if (GetEnvironmentVariable(kPythonPath, oldpath, sizeof(oldpath)) == 0) {
     SetEnvironmentVariableW(kPythonPath, dir.value().c_str());
   } else if (!wcsstr(oldpath, dir.value().c_str())) {
     std::wstring newpath(oldpath);
@@ skipping 235 matching lines @@
                   "certificate to your trusted roots for this test to work. "
                   "For more info visit:\n"
                   "http://dev.chromium.org/developers/testing\n";
     return false;
   }
 #endif
   return true;
 }
 
 }  // namespace net