Make -w wipe a standalone flag.

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>
 #if defined(__MAC_10_12) && __MAC_OS_X_VERSION_MAX_ALLOWED >= __MAC_10_12
 #include <getopt.h>
 #include <string>
 
 namespace {
 
@@ skipping 318 matching lines @@
              sdk_version);
     PrintSupportedDevices(simctl_list);
     exit(kExitInvalidArguments);
   }
 
   if (wants_print_home) {
     PrintDeviceHome(udid);
     exit(kExitSuccess);
   }
 
+  KillSimulator();
+  if (wants_wipe) {
+    WipeDevice(udid);
+    printf("Device wiped.\n");
+    exit(kExitSuccess);
+  }
+
   // There should be at least one arg left, specifying the app path. Any
   // additional args are passed as arguments to the app.
   if (optind < argc) {
     NSString* unresolved_path = [[NSFileManager defaultManager]
         stringWithFileSystemRepresentation:argv[optind]
                                     length:strlen(argv[optind])];
     app_path = ResolvePath(unresolved_path);
     if (!app_path) {
       LogError(@"Unable to resolve app_path %@", unresolved_path);
       exit(kExitInvalidArguments);
     }
 
     if (++optind < argc) {
       NSString* unresolved_path = [[NSFileManager defaultManager]
           stringWithFileSystemRepresentation:argv[optind]
                                       length:strlen(argv[optind])];
       xctest_path = ResolvePath(unresolved_path);
       if (!xctest_path) {
         LogError(@"Unable to resolve xctest_path %@", unresolved_path);
         exit(kExitInvalidArguments);
       }
     }
   } else {
     LogError(@"Unable to parse command line arguments.");
     PrintUsage();
     exit(kExitInvalidArguments);
   }
 
-  KillSimulator();
-  if (wants_wipe) {
-    WipeDevice(udid);
-  }
-
   RunApplication(app_path, xctest_path, udid, app_env, cmd_args);
   KillSimulator();
   return kExitSuccess;
 }
 #else
 #import <Appkit/Appkit.h>
 #include <asl.h>
 #import <Foundation/Foundation.h>
 #include <libgen.h>
 #include <stdarg.h>
@@ skipping 852 matching lines @@
   }
 
   // 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;
 }
 
 #endif