Update some uses of UTF conversions in chrome/browser to use the base:: namespace.

chrome/browser/spellchecker/misspelling.h

Index: chrome/browser/spellchecker/misspelling.h
diff --git a/chrome/browser/spellchecker/misspelling.h b/chrome/browser/spellchecker/misspelling.h
index 6fe98dd8b4c2d401cec44e51e583ae30c1755f99..7db83f708ce8f8a542fca5c9e7458234b2476edf 100644
--- a/chrome/browser/spellchecker/misspelling.h
+++ b/chrome/browser/spellchecker/misspelling.h
@@ -19,11 +19,11 @@
 
 // Stores user feedback to a spellcheck suggestion. Sample usage:
 //    Misspelling misspelling.
-//    misspelling.context = ASCIIToUTF16("Helllo world");
+//    misspelling.context = base::ASCIIToUTF16("Helllo world");
 //    misspelling.location = 0;
 //    misspelling.length = 6;
 //    misspelling.suggestions =
-//        std::vector<base::string16>(1, ASCIIToUTF16("Hello"));
+//        std::vector<base::string16>(1, base::ASCIIToUTF16("Hello"));
 //    misspelling.hash = GenerateRandomHash();
 //    misspelling.action.type = SpellcheckAction::TYPE_SELECT;
 //    misspelling.action.index = 0;