Add more string_util functions to base namespace.

ui/message_center/views/bounded_label_unittest.cc

Index: ui/message_center/views/bounded_label_unittest.cc
diff --git a/ui/message_center/views/bounded_label_unittest.cc b/ui/message_center/views/bounded_label_unittest.cc
index 9744aee6df8cafec891412253420f378825acaac..7c3a6a6bf1fa390f59f9cce8df8a660f4309e85d 100644
--- a/ui/message_center/views/bounded_label_unittest.cc
+++ b/ui/message_center/views/bounded_label_unittest.cc
@@ -38,7 +38,7 @@ class BoundedLabelTest : public testing::Test {
     const char kPeriods[] = "...";
     const char kEllipses[] = "\xE2\x80\xA6";
     std::string result = string;
-    ReplaceSubstringsAfterOffset(&result, 0, kPeriods, kEllipses);
+    base::ReplaceSubstringsAfterOffset(&result, 0, kPeriods, kEllipses);
     return base::UTF8ToUTF16(result);
   }