Switch [String]FileWriter to use new file_io.h functions/types

tools/generate_dump.cc

 // Copyright 2014 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 134 matching lines @@
       suspend.reset(new ScopedTaskSuspend(task));
     }
 
     ProcessSnapshotMac process_snapshot;
     if (!process_snapshot.Initialize(task)) {
       return EXIT_FAILURE;
     }
 
     FileWriter file_writer;
     if (!file_writer.Open(base::FilePath(options.dump_path),
-                          O_WRONLY | O_CREAT | O_TRUNC,
-                          0644)) {
+                          FileWriteMode::kTruncateOrCreate,
+                          true)) {
       return EXIT_FAILURE;
     }
 
     MinidumpFileWriter minidump;
     minidump.InitializeFromSnapshot(&process_snapshot);
     if (!minidump.WriteEverything(&file_writer)) {
       if (unlink(options.dump_path.c_str()) != 0) {
         PLOG(ERROR) << "unlink";
       }
       return EXIT_FAILURE;
     }
   }
 
   return EXIT_SUCCESS;
 }
 
 }  // namespace
 }  // namespace crashpad
 
 int main(int argc, char* argv[]) {
   return crashpad::GenerateDumpMain(argc, argv);
 }