Add base:: to string16s in chrome/.

chrome/installer/gcapi/gcapi_last_run_test.cc

Index: chrome/installer/gcapi/gcapi_last_run_test.cc
diff --git a/chrome/installer/gcapi/gcapi_last_run_test.cc b/chrome/installer/gcapi/gcapi_last_run_test.cc
index ba57e59d6f8db275bdee4d587219a74b09d12bba..02a19748df8a9c3b925b43f3e8279f7ea72cb628 100644
--- a/chrome/installer/gcapi/gcapi_last_run_test.cc
+++ b/chrome/installer/gcapi/gcapi_last_run_test.cc
@@ -55,7 +55,7 @@ class GCAPILastRunTest : public ::testing::Test {
     return SetLastRunTimeString(base::Int64ToString16(last_run_time));
   }
 
-  bool SetLastRunTimeString(const string16& last_run_time_string) {
+  bool SetLastRunTimeString(const base::string16& last_run_time_string) {
     const wchar_t* base_path = google_update::kRegPathClientState;
     std::wstring path(base_path);
     path += L"\\";