Make use of ElapsedTimer API for the 'gen' command.

tools/gn/command_gyp.cc

 // Copyright (c) 2013 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.
 
 #include <iostream>
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/strings/string_number_conversions.h"
-#include "base/time/time.h"
+#include "base/timer/elapsed_timer.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/gyp_helper.h"
 #include "tools/gn/gyp_target_writer.h"
 #include "tools/gn/location.h"
 #include "tools/gn/parser.h"
 #include "tools/gn/setup.h"
 #include "tools/gn/source_file.h"
@@ skipping 295 matching lines @@
     "    direct_dependen_configs = [ \":gyp_target_config\" ]\n"
     "  }\n"
     "\n"
     "  executable(\"my_app\") {\n"
     "    deps = [ \":gyp_target\" ]\n"
     "    gyp_file = \"//foo/myapp.gyp\"\n"
     "    sources = ...\n"
     "  }\n";
 
 int RunGyp(const std::vector<std::string>& args) {
-  const CommandLine* cmdline = CommandLine::ForCurrentProcess();
-
-  base::TimeTicks begin_time = base::TimeTicks::Now();
+  base::ElapsedTimer timer;
 
   // Deliberately leaked to avoid expensive process teardown.
   Setup* setup_debug = new Setup;
   if (!setup_debug->DoSetup())
     return 1;
   const char kIsDebug[] = "is_debug";
 
   SourceDir base_build_dir = setup_debug->build_settings().build_dir();
   setup_debug->build_settings().SetBuildDir(
       AppendDirSuffix(base_build_dir, ".Debug"));
@@ skipping 58 matching lines @@
   std::pair<int, int> counts =
       WriteGypFiles(setup_debug, setup_release,
                     setup_host_debug, setup_host_release,
                     setup_debug64, setup_release64,
                     &err);
   if (err.has_error()) {
     err.PrintToStdout();
     return 1;
   }
 
-  // Timing info.
-  base::TimeTicks end_time = base::TimeTicks::Now();
-  if (!cmdline->HasSwitch(kSwitchQuiet)) {
+  base::TimeDelta elapsed_time = timer.Elapsed();
+
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(kSwitchQuiet)) {
     OutputString("Done. ", DECORATION_GREEN);
 
     std::string stats = "Wrote " +
         base::IntToString(counts.first) + " targets to " +
         base::IntToString(counts.second) + " GYP files read from " +
         base::IntToString(
             setup_debug->scheduler().input_file_manager()->GetInputFileCount())
         + " GN files in " +
-        base::IntToString((end_time - begin_time).InMilliseconds()) + "ms\n";
+        base::IntToString(elapsed_time.InMilliseconds()) + "ms\n";
 
     OutputString(stats);
   }
 
   return 0;
 }
 
 }  // namespace commands