Update some uses of char16 to use the base:: namespace.

chrome/renderer/searchbox/searchbox_extension.cc

Index: chrome/renderer/searchbox/searchbox_extension.cc
diff --git a/chrome/renderer/searchbox/searchbox_extension.cc b/chrome/renderer/searchbox/searchbox_extension.cc
index d4cafe43b07f9b1e26b4363db76e9d8c24c27c10..f56ce48c84f1e8922f47ef0b17ac13d31baac1fa 100644
--- a/chrome/renderer/searchbox/searchbox_extension.cc
+++ b/chrome/renderer/searchbox/searchbox_extension.cc
@@ -58,7 +58,7 @@ const char kRTLHtmlTextDirection[] = "rtl";
 // Converts a V8 value to a string16.
 base::string16 V8ValueToUTF16(v8::Handle<v8::Value> v) {
   v8::String::Value s(v);
-  return base::string16(reinterpret_cast<const char16*>(*s), s.length());
+  return base::string16(reinterpret_cast<const base::char16*>(*s), s.length());
 }
 
 // Converts string16 to V8 String.