chromeos: Use stl utilities from the base namespace

chromeos/settings/timezone_settings_unittest.cc

Index: chromeos/settings/timezone_settings_unittest.cc
diff --git a/chromeos/settings/timezone_settings_unittest.cc b/chromeos/settings/timezone_settings_unittest.cc
index 7f7a64268e3af56f1b5405814a38d04cf1a6a860..3c9e129ac8fd0a30ea4bfe07d946fc6b945123bb 100644
--- a/chromeos/settings/timezone_settings_unittest.cc
+++ b/chromeos/settings/timezone_settings_unittest.cc
@@ -40,7 +40,7 @@ class KnownTimeZoneTest : public testing::Test {
     }
   }
 
-  void TearDown() override { STLDeleteElements(&timezones_); }
+  void TearDown() override { base::STLDeleteElements(&timezones_); }
 
  protected:
   std::vector<TimeZone*> timezones_;