Move string tokenizer to base/strings.

chrome/browser/metrics/thread_watcher.cc

Index: chrome/browser/metrics/thread_watcher.cc
diff --git a/chrome/browser/metrics/thread_watcher.cc b/chrome/browser/metrics/thread_watcher.cc
index 8b75c3f181b07a80413a3f27cd047975935e3364..4aa26f7fd5ab5aec3cac0c4377fe8ca02ffc63a4 100644
--- a/chrome/browser/metrics/thread_watcher.cc
+++ b/chrome/browser/metrics/thread_watcher.cc
@@ -12,7 +12,7 @@
 #include "base/lazy_instance.h"
 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
-#include "base/string_tokenizer.h"
+#include "base/strings/string_tokenizer.h"
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "chrome/browser/metrics/metrics_service.h"
@@ -542,7 +542,7 @@ void ThreadWatcherList::ParseCommandLine(
         command_line.GetSwitchValueASCII(switches::kCrashOnHangThreads);
     has_command_line_overwrite = true;
   }
-  StringTokenizer tokens(crash_on_hang_thread_names, ",");
+  base::StringTokenizer tokens(crash_on_hang_thread_names, ",");
   std::vector<std::string> values;
   while (tokens.GetNext()) {
     const std::string& token = tokens.token();