Remove 'using base::string16;' from base/strings/string16.h and remove temporary

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index c311d2df1210a45d8c14e7a30e0586fc3cb6787a..8e641cc3d222b376329e7187633741b44045745f 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -511,7 +511,7 @@ void RenderWidgetHostViewAndroid::OnStartContentIntent(
 }
 
 void RenderWidgetHostViewAndroid::OnSmartClipDataExtracted(
-    const string16& result) {
+    const base::string16& result) {
   // Custom serialization over IPC isn't allowed normally for security reasons.
   // Since this feature is only used in (single-process) WebView, there are no
   // security issues. Enforce that it's only called in single process mode.