Update uses of UTF conversions in content/ to use the base:: namespace.

content/common/plugin_list.cc

Index: content/common/plugin_list.cc
diff --git a/content/common/plugin_list.cc b/content/common/plugin_list.cc
index d623fad337d656adbce2808a0e8eb3214cb1ccd9..df1f77b3441bc52fe15986729dfbe41a4789b55f 100644
--- a/content/common/plugin_list.cc
+++ b/content/common/plugin_list.cc
@@ -153,7 +153,7 @@ bool PluginList::ParseMimeTypes(
       // On Windows, the description likely has a list of file extensions
       // embedded in it (e.g. "SurfWriter file (*.swr)"). Remove an extension
       // list from the description if it is present.
-      size_t ext = mime_type.description.find(ASCIIToUTF16("(*"));
+      size_t ext = mime_type.description.find(base::ASCIIToUTF16("(*"));
       if (ext != base::string16::npos) {
         if (ext > 1 && mime_type.description[ext - 1] == ' ')
           ext--;