Use base namespace for string16 in components and cloud_print.

components/autofill/core/browser/validation.cc

Index: components/autofill/core/browser/validation.cc
diff --git a/components/autofill/core/browser/validation.cc b/components/autofill/core/browser/validation.cc
index 57a096e931247f9b5889ede35e1790a1920794f8..b4b3a5e3f89d9110adbc3b16d81a1ad5ef161622 100644
--- a/components/autofill/core/browser/validation.cc
+++ b/components/autofill/core/browser/validation.cc
@@ -155,8 +155,8 @@ bool IsValidZip(const base::string16& text) {
   return MatchesPattern(text, kZipPattern);
 }
 
-bool IsSSN(const string16& text) {
-  string16 number_string;
+bool IsSSN(const base::string16& text) {
+  base::string16 number_string;
   base::RemoveChars(text, kSSNSeparators, &number_string);
 
   // A SSN is of the form AAA-GG-SSSS (A = area number, G = group number, S =