mac: Revise incorrect comments about EXC_RESOURCE and EXC_GUARD

handler/mac/crash_report_exception_handler.cc

 // Copyright 2015 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 92 matching lines @@
   // from the process itself to be suspicious.
   const pid_t pid = process_snapshot.ProcessID();
   pid_t audit_pid = AuditPIDFromMachMessageTrailer(trailer);
   if (audit_pid != -1 && audit_pid != 0) {
     if (audit_pid != pid) {
       LOG(WARNING) << "exception for pid " << pid << " sent by pid "
                    << audit_pid;
     }
   }
 
-  if (IsExceptionNonfatalResource(exception, code[0], pid)) {
-    // Swallow non-fatal resource exceptions.
-    //
-    // Normally, all EXC_RESOURCE exceptions go to the host-level EXC_RESOURCE
-    // handler, com.apple.ReportCrash.root, which invokes spindump to handle
-    // them. These non-fatal exceptions are never user-visible and are not
-    // currently of interest to Crashpad. Returning success here gets the
-    // process going again quickly, without generating a crash report.
-    //
-    // Alternatively, this could return KERN_FAILURE to let the exception go to
-    // the host-level handler, but there doesn’t seem to be much value in doing
-    // so.
-    ExcServerCopyState(
-        behavior, old_state, old_state_count, new_state, new_state_count);
-    return ExcServerSuccessfulReturnValue(exception, behavior, false);
-  }
-
   CrashpadInfoClientOptions client_options;
   process_snapshot.GetCrashpadOptions(&client_options);
 
-  if (client_options.crashpad_handler_behavior != TriState::kDisabled) {
+  if (client_options.crashpad_handler_behavior != TriState::kDisabled &&
+      !IsExceptionNonfatalResource(exception, code[0], pid)) {
+    // Non-fatal resource exceptions are never user-visible and are not
+    // currently of interest to Crashpad.
+
     if (!process_snapshot.InitializeException(behavior,
                                               thread,
                                               exception,
                                               code,
                                               code_count,
                                               *flavor,
                                               old_state,
                                               old_state_count)) {
       return KERN_FAILURE;
     }
@@ skipping 46 matching lines @@
        exception == EXC_RESOURCE ||
        exception == EXC_GUARD)) {
     // Don’t forward simulated exceptions such as kMachExceptionSimulated to the
     // system crash reporter. Only forward the types of exceptions that it would
     // receive under normal conditions. Although the system crash reporter is
     // able to deal with other exceptions including simulated ones, forwarding
     // them to the system crash reporter could present the system’s crash UI for
     // processes that haven’t actually crashed, and could result in reports not
     // actually associated with crashes being sent to the operating system
     // vendor.
-    //
-    // Note that normally, EXC_RESOURCE and EXC_GUARD exceptions are sent to the
-    // system-level com.apple.ReportCrash.Root job, and not to the user-level
-    // job that they are forwarded to here.
     base::mac::ScopedMachSendRight
         system_crash_reporter_handler(SystemCrashReporterHandler());
     if (system_crash_reporter_handler) {
       // Make copies of mutable out parameters so that the system crash reporter
       // can’t influence the state returned by this method.
       thread_state_flavor_t flavor_forward = *flavor;
       mach_msg_type_number_t new_state_forward_count = *new_state_count;
       std::vector<natural_t> new_state_forward(
           new_state, new_state + new_state_forward_count);
 
@@ skipping 23 matching lines @@
     }
   }
 
   ExcServerCopyState(
       behavior, old_state, old_state_count, new_state, new_state_count);
 
   return ExcServerSuccessfulReturnValue(exception, behavior, false);
 }
 
 }  // namespace crashpad