Add base:: to string16 in rlz/.

rlz/lib/machine_id.h

Index: rlz/lib/machine_id.h
diff --git a/rlz/lib/machine_id.h b/rlz/lib/machine_id.h
index af58c8ed92795ea676bca5babd5f454c69286e96..312f669470151fa233612b2897c65a15e9cf12d7 100644
--- a/rlz/lib/machine_id.h
+++ b/rlz/lib/machine_id.h
@@ -21,10 +21,10 @@ bool GetMachineId(std::string* machine_id);
 // Retrieves a raw machine identifier string and a machine-specific
 // 4 byte value. GetMachineId() will SHA1 |data|, append |more_data|, compute
 // the Crc8 of that, and return a hex-encoded string of that data.
-bool GetRawMachineId(string16* data, int* more_data);
+bool GetRawMachineId(base::string16* data, int* more_data);
 
 namespace testing {
-bool GetMachineIdImpl(const string16& sid_string,
+bool GetMachineIdImpl(const base::string16& sid_string,
                       int volume_id,
                       std::string* machine_id);
 }  // namespace testing