Add explicit base namespace to string16 users.

chrome/common/importer/firefox_importer_utils_win.cc

Index: chrome/common/importer/firefox_importer_utils_win.cc
diff --git a/chrome/common/importer/firefox_importer_utils_win.cc b/chrome/common/importer/firefox_importer_utils_win.cc
index 0f0b57fe8efc64de534c99c56024e5343afe73ed..5cc9f99a4fe2af6e031317d54cf04d73bd161dfb 100644
--- a/chrome/common/importer/firefox_importer_utils_win.cc
+++ b/chrome/common/importer/firefox_importer_utils_win.cc
@@ -47,7 +47,7 @@ int GetCurrentFirefoxMajorVersionFromRegistry() {
 
 base::FilePath GetFirefoxInstallPathFromRegistry() {
   // Detects the path that Firefox is installed in.
-  string16 registry_path = kFirefoxPath;
+  base::string16 registry_path = kFirefoxPath;
   wchar_t buffer[MAX_PATH];
   DWORD buffer_length = sizeof(buffer);
   base::win::RegKey reg_key(HKEY_LOCAL_MACHINE, registry_path.c_str(),
@@ -57,7 +57,7 @@ base::FilePath GetFirefoxInstallPathFromRegistry() {
   if (result != ERROR_SUCCESS)
     return base::FilePath();
 
-  registry_path += L"\\" + string16(buffer) + L"\\Main";
+  registry_path += L"\\" + base::string16(buffer) + L"\\Main";
   buffer_length = sizeof(buffer);
   base::win::RegKey reg_key_directory(HKEY_LOCAL_MACHINE,
                                       registry_path.c_str(), KEY_READ);