mac: Add CrashpadClient::UseSystemDefaultHandler()

util/mach/mach_extensions.h

Index: util/mach/mach_extensions.h
diff --git a/util/mach/mach_extensions.h b/util/mach/mach_extensions.h
index 4f2861bf6446e2be186e3c6bc31956e970aa1c3b..a569aa8ca8b0c59d4f049e35a4f20f24fd679615 100644
--- a/util/mach/mach_extensions.h
+++ b/util/mach/mach_extensions.h
@@ -115,6 +115,20 @@ exception_mask_t ExcMaskAll();
 //! support is present.
 exception_mask_t ExcMaskValid();
 
+//! \brief Obtains the system’s default Mach exception handler for crash-type
+//!     exceptions.
+//!
+//! This is obtained by looking up `"com.apple.ReportCrash"` with the bootstrap
+//! server. The service name comes from the first launch agent loaded by
+//! `launchd` with a `MachServices` entry having `ExceptionServer` set. This
+//! launch agent is normally loaded from
+//! `/System/Library/LaunchAgents/com.apple.ReportCrash.plist`.
+//!
+//! \return On success, a send right to a Mach exception handler corresponding
+//!     to the system’s default crash reporter. On failure, `MACH_PORT_NULL`,
+//!     with a message logged.
+exception_handler_t SystemCrashReporterHandler();

[Robert Sesek, 2015/10/02 18:30:19]

I think this could return a ScopedMachSendRight, since ScopedGeneric now has
move support.

+
 }  // namespace crashpad
 
 #endif  // CRASHPAD_UTIL_MACH_MACH_EXTENSIONS_H_