[Mac] Use Crashpad in the AlertNotificationService.xpc.

chrome/browser/ui/cocoa/notifications/xpc_mach_port.h

+// Copyright 2017 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.
+
+#ifndef CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_XPC_MACH_PORT_H_
+#define CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_XPC_MACH_PORT_H_
+
+#import <Foundation/Foundation.h>
+
+#include "base/mac/scoped_mach_port.h"
+
+// An XPC transit type for Mach send rights. While this class conforms to
+// NSSecureCoding, it is only valid to use the NSCoding methods for XPC.
+//
+// The public XPC APIs do not proivde any way to transfer Mach ports. Using the
+// C-based API, the functions for setting/creating an XPC Mach port object can
+// simply be forward-declared. But the Foundation API does not provide any way
+// to pass a Mach port as part of a message. The OS_xpc_object Obj-C types
+// do not conform to NSSecureCoding either, so they cannot be used to transport
+// ports via the Foundation-level API.
+//
+// Instead, this class encodes Mach port OOL data using the private

[Mark Mentovai, 2017/03/14 23:24:52]

Seems like we might want to have a test for at least this portion.

[Robert Sesek, 2017/03/15 19:22:09]

Agreed, but the "how" of that is not-trivial. While we can create an
NSXPCEncoder/NSXPCDecoder, I'm not sure how to extract the resulting data so as
to test round-tripping the encode through the decode. It's really not possible
to set up an entire XPCService in unit_tests for this, either.

+// NSXPCEncoder and NSXPCDecoder APIs. These APIs expose methods by which
+// xpc_objct_t's (and their OS_object-bridged-siblings) can be encoded into a
+// Foundation-level XPC message.
+@interface CrXPCMachPort : NSObject<NSSecureCoding>
+
+// Creates a new transit Mach port by taking ownership of the |sendRight|.
+- (instancetype)initWithMachSendRight:(base::mac::ScopedMachSendRight)sendRight;
+
+// Relinquishes ownership of the Mach port to the caller.
+- (base::mac::ScopedMachSendRight)takeRight;
+
+@end
+
+#endif  // CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_XPC_MACH_PORT_H_