Add base:: to string16s in win8/.

win8/metro_driver/secondary_tile.h

Index: win8/metro_driver/secondary_tile.h
diff --git a/win8/metro_driver/secondary_tile.h b/win8/metro_driver/secondary_tile.h
index 9740864bbdf8032943825b04d07442a1a9ccd159..1166e1313c0af3b324b5fa56189d6e1f2b2d8680 100644
--- a/win8/metro_driver/secondary_tile.h
+++ b/win8/metro_driver/secondary_tile.h
@@ -9,18 +9,18 @@
 #include "base/win/metro.h"
 
 extern "C" __declspec(dllexport)
-BOOL MetroIsPinnedToStartScreen(const string16& tile_id);
+BOOL MetroIsPinnedToStartScreen(const base::string16& tile_id);
 
 extern "C" __declspec(dllexport)
 void MetroUnPinFromStartScreen(
-    const string16& tile_id,
+    const base::string16& tile_id,
     const base::win::MetroPinUmaResultCallback& callback);
 
 extern "C" __declspec(dllexport)
 void MetroPinToStartScreen(
-    const string16& tile_id,
-    const string16& title,
-    const string16& url,
+    const base::string16& tile_id,
+    const base::string16& title,
+    const base::string16& url,
     const base::FilePath& logo_path,
     const base::win::MetroPinUmaResultCallback& callback);