Allow $TMPDIR to set temporary directory on OS X.

remoting/host/mac/me2me_preference_pane.mm

 // 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.
 
 #import "remoting/host/mac/me2me_preference_pane.h"
 
 #import <Cocoa/Cocoa.h>
 #include <CommonCrypto/CommonHMAC.h>
 #include <errno.h>
 #include <launch.h>
 #import <PreferencePanes/PreferencePanes.h>
 #import <SecurityInterface/SFAuthorizationView.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 #include <fstream>
 #include <memory>
 
+#include "base/files/file_util.h"
 #include "base/mac/authorization_util.h"
 #include "base/mac/launchd.h"
 #include "base/mac/mac_logging.h"
 #include "base/mac/scoped_launch_data.h"
 #include "base/posix/eintr_wrapper.h"
 #include "remoting/host/host_config.h"
 #include "remoting/host/mac/constants_mac.h"
 #import "remoting/host/mac/me2me_preference_pane_confirm_pin.h"
 #import "remoting/host/mac/me2me_preference_pane_disable.h"
 #include "remoting/host/pin_hash.h"
 #include "third_party/jsoncpp/source/include/json/reader.h"
 #include "third_party/jsoncpp/source/include/json/writer.h"
 
 namespace {
 
 bool GetTemporaryConfigFilePath(std::string* path) {
-  NSString* filename = NSTemporaryDirectory();
-  if (filename == nil)
+  base::FilePath ret;
+
+  if (!base::GetTempDir(&ret)) {
     return false;
+  }
 
-  *path = [[NSString stringWithFormat:@"%@/%s",
-            filename, remoting::kHostConfigFileName] UTF8String];
+  ret = ret.Append(remoting::kHostConfigFileName);
+
+  // This should be safe on OS X because utf8 is always supported.
+  *path = ret.AsUTF8Unsafe();
   return true;
 }
 
 bool IsConfigValid(const remoting::JsonHostConfig* config) {
   std::string value;
   return (config->GetString(remoting::kHostIdConfigPath, &value) &&
           config->GetString(remoting::kHostSecretHashConfigPath, &value) &&
           config->GetString(remoting::kXmppLoginConfigPath, &value));
 }
 
@@ skipping 528 matching lines @@
   NSArray* arguments = [NSArray arrayWithObjects:@"--relaunch-prefpane", nil];
   [task setLaunchPath:command];
   [task setArguments:arguments];
   [task setStandardInput:[NSPipe pipe]];
   [task launch];
   [task release];
   [NSApp terminate:nil];
 }
 
 @end