In iossim, use the user's home directory if no override is given.

testing/iossim/iossim.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 <Foundation/Foundation.h>
 #include <asl.h>
 #include <libgen.h>
 #include <stdarg.h>
 #include <stdio.h>
 
@@ skipping 891 matching lines @@
   else {
     LogError(@"Invalid device name: %@. Must begin with 'iPhone' or 'iPad'",
              deviceName);
     exit(kExitInvalidArguments);
   }
 #endif  // !defined(IOSSIM_USE_XCODE_6)
 
   // Set up the user home directory for the simulator only if a non-default
   // value was specified.
   if (simHomePath) {
     if (!InitializeSimulatorUserHome(simHomePath)) {

[smut, 2014/07/16 18:47:37]

Can you move this check below so it tries to initialize the fallback simHomePath
as well?

[lliabraa, 2014/07/16 18:49:53]

It's not necessary to initialize the directory when we're using the default

[smut, 2014/07/16 18:52:20]

Ok. I wasn't sure what this did (e.g. maybe it checks write permissions, which
might be necessary).

       LogError(@"Unable to initialize home directory for simulator: %@",
                simHomePath);
       exit(kExitInitializationFailure);
     }
+  } else {
+    simHomePath = NSHomeDirectory();
   }
 
   // Create the config and simulator session.
   DTiPhoneSimulatorSessionConfig* config = BuildSessionConfig(appSpec,
                                                               systemRoot,
                                                               stdioPath,
                                                               stdioPath,
                                                               appArgs,
                                                               appEnv,
                                                               deviceFamily,
@@ skipping 19 matching lines @@
              [error localizedDescription],
              [error domain], static_cast<long int>([error code]));
   }
 
   // Note that this code is only executed if the simulator fails to start
   // because once the main run loop is started, only the delegate calling
   // exit() will end the program.
   [pool drain];
   return kExitFailure;
 }