Work around iossim compile issues on latest Xcode beta.

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 <Appkit/Appkit.h>
 #include <asl.h>
 #import <Foundation/Foundation.h>
 #include <libgen.h>
 #include <stdarg.h>
 #include <stdio.h>
 
 // An executable (iossim) that runs an app in the iOS Simulator.
 // Run 'iossim -h' for usage information.
 //
 // For best results, the iOS Simulator application should not be running when
 // iossim is invoked.
 //
 // Headers for iPhoneSimulatorRemoteClient and other frameworks used in this
 // tool are generated by class-dump, via GYP.
 // (class-dump is available at http://www.codethecode.com/projects/class-dump/)
 //
 // However, there are some forward declarations required to get things to
 // compile.
 
 @class DVTStackBacktrace;
 #import "DVTFoundation.h"
 
+// TODO(crbug.com/619982): The latest Xcode beta does not include the proper
+// headers to use or compile iossim.  Define them here so iossim can compile for
+// now. Unwind this #ifdef if future betas work, or replace and remove iossim.
+#if defined(__MAC_10_12) && __MAC_OS_X_VERSION_MAX_ALLOWED >= __MAC_10_12
+@class SimDevice;
+@class SimDevicePasteboardConnection;
+@class SimDeviceNotificationManager;
+@class SimMachPortServer;
+@class SimPasteboardItem;
+#endif
+
 @protocol SimBridge;
 @class DVTSimulatorApplication;
 @class SimDeviceSet;
 @class SimDeviceType;
 @class SimProfilesPathMonitor;
 @class SimRuntime;
 @class SimServiceConnectionManager;
 #import "CoreSimulator.h"
 
 @interface DVTPlatform : NSObject
@@ skipping 12 matching lines @@
 // by the iPhoneSimulatorRemoteClient framework, but not defined in the object
 // file, so it must be defined here before importing the generated
 // iPhoneSimulatorRemoteClient.h file.
 @protocol DTiPhoneSimulatorSessionDelegate
 - (void)session:(DTiPhoneSimulatorSession*)session
     didEndWithError:(NSError*)error;
 - (void)session:(DTiPhoneSimulatorSession*)session
        didStart:(BOOL)started
       withError:(NSError*)error;
 @end
+
+// TODO(crbug.com/619982): The latest Xcode beta does not include the proper
+// headers to use or compile iossim.  Define them here so iossim can compile for
+// now. Unwind this #ifdef if future betas work, or replace and remove iossim.
+#if defined(__MAC_10_12) && __MAC_OS_X_VERSION_MAX_ALLOWED >= __MAC_10_12
+@class SimRuntime;
+@interface DTiPhoneSimulatorSystemRoot : NSObject<NSCopying> {
+  SimRuntime* _runtime;
+}
++ (id)rootWithSDKVersion:(id)arg1;
+@property(readonly) SimRuntime* runtime;
+@property(readonly, copy) NSString* sdkVersion;
+@end
+#endif
+
 #import "DVTiPhoneSimulatorRemoteClient.h"
 
 // An undocumented system log key included in messages from launchd. The value
 // is the PID of the process the message is about (as opposed to launchd's PID).
 #define ASL_KEY_REF_PID "RefPID"
 
 namespace {
 
 // Name of environment variables that control the user's home directory in the
 // simulator.
@@ skipping 789 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;
 }