Convert string16 to base::string16 in content.

content/public/browser/plugin_service.h

Index: content/public/browser/plugin_service.h
diff --git a/content/public/browser/plugin_service.h b/content/public/browser/plugin_service.h
index 8c28948d21af534755483edb377d70d46ebea467..76e6ddad374b61cae2189f7f38cf707fdaf8253c 100644
--- a/content/public/browser/plugin_service.h
+++ b/content/public/browser/plugin_service.h
@@ -89,7 +89,7 @@ class PluginService {
   // Returns the display name for the plugin identified by the given path. If
   // the path doesn't identify a plugin, or the plugin has no display name,
   // this will attempt to generate a display name from the path.
-  virtual string16 GetPluginDisplayNameByPath(
+  virtual base::string16 GetPluginDisplayNameByPath(
       const base::FilePath& plugin_path) = 0;
 
   // Asynchronously loads plugins if necessary and then calls back to the