Implement CurrentProcessInfo::CreationTime() for Linux.

chrome/browser/ui/app_list/app_list_service.cc

 // Copyright 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 "chrome/browser/ui/app_list/app_list_service.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/process/process_info.h"
@@ skipping 29 matching lines @@
 void AppListService::RecordShowTimings(const CommandLine& command_line) {
   // The presence of kOriginalProcessStartTime implies that another process
   // has sent us its command line to handle, ie: we are already running.
   if (command_line.HasSwitch(switches::kOriginalProcessStartTime)) {
     base::TimeDelta elapsed = GetTimeFromOriginalProcessStart(command_line);
     if (command_line.HasSwitch(switches::kFastStart))
       UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListWarmStartFast", elapsed);
     else
       UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListWarmStart", elapsed);
   } else {
-    // base::CurrentProcessInfo::CreationTime() is only defined on win/mac.
-#if defined(OS_WIN) || defined(OS_MACOSX)
     UMA_HISTOGRAM_LONG_TIMES(
         "Startup.ShowAppListColdStart",
         base::Time::Now() - *base::CurrentProcessInfo::CreationTime());
-#endif
   }
 }