Reland of Work around simctl error when moving from Xcode 7 to Xcode 8.

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 266 matching lines @@
             }
           }
           printf("%s", [log UTF8String]);
         };
     [task setStandardError:stderr_pipe];
   }
   [task run];
 }
 
 int main(int argc, char* const argv[]) {
+  // When the last running simulator is from Xcode 7, an Xcode 8 run will yeild
+  // a failure to "unload a stale CoreSimulatorService job" message.  Sending a
+  // hidden simctl to do something simple (list devices) helpfully works around
+  // this issue.
+  XCRunTask* workaround_task = [[[XCRunTask alloc]
+      initWithArguments:@[ @"simctl", @"list", @"-j" ]] autorelease];
+  [workaround_task setStandardOutput:nil];
+  [workaround_task setStandardError:nil];
+  [workaround_task run];
+
   NSString* app_path = nil;
   NSString* xctest_path = nil;
   NSString* cmd_args = nil;
   NSString* device_name = @"iPhone 6s";
   bool wants_wipe = false;
   bool wants_print_home = false;
   NSDictionary* simctl_list = GetSimulatorList();
   float sdk = 0;
   for (NSDictionary* runtime in Runtimes(simctl_list)) {
     sdk = fmax(sdk, [runtime[@"version"] floatValue]);
@@ skipping 961 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