Don’t use using directives (“using namespace”) in tools

tools/on_demand_service_tool.mm

 // 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 12 matching lines @@
 
 #include <string>
 #include <vector>
 
 #include "base/mac/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "tools/tool_support.h"
 #include "util/mac/service_management.h"
 #include "util/stdlib/objc.h"
 
+namespace crashpad {
 namespace {
 
-using namespace crashpad;
-
 void Usage(const std::string& me) {
   fprintf(stderr,
 "Usage: %s -L -l LABEL [OPTION]... COMMAND [ARG]...\n"
 "       %s -U -l LABEL\n"
 "Load and unload on-demand Mach services from launchd.\n"
 "\n"
 "  -L, --load                  load (submit) the job identified by --label;\n"
 "                              COMMAND must be specified\n"
 "  -U, --unload                unload (remove) the job identified by --label\n"
 "  -l, --label=LABEL           identify the job to launchd with LABEL\n"
 "  -m, --mach_service=SERVICE  register SERVICE with the bootstrap server\n"
 "      --help                  display this help and exit\n"
 "      --version               output version information and exit\n",
           me.c_str(),
           me.c_str());
   ToolSupport::UsageTail(me);
 }
 
-}  // namespace
-
-int main(int argc, char* argv[]) {
+int OnDemandServiceToolMain(int argc, char* argv[]) {
   const std::string me(basename(argv[0]));
 
   enum Operation {
     kOperationUnknown = 0,
     kOperationLoadJob,
     kOperationUnloadJob,
   };
 
   enum OptionFlags {
     // “Short” (single-character) options.
@@ skipping 115 matching lines @@
 
       return EXIT_SUCCESS;
     }
 
     default: {
       ToolSupport::UsageHint(me, "must provide -L or -U");
       return EXIT_FAILURE;
     }
   }
 }
+
+}  // namespace
+}  // namespace crashpad
+
+int main(int argc, char* argv[]) {
+  return crashpad::OnDemandServiceToolMain(argc, argv);
+}