Replace base::NullableString16(bool) usage with default constructor.

Review URL: https://chromiumcodereview.appspot.com/17327004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@206922 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 7f9f6180b8ccd0bd6cdb81572037ca3e0baba988
diff --git a/base/strings/nullable_string16.h b/base/strings/nullable_string16.h
index 16dcfe2..e35e3d1 100644
--- a/base/strings/nullable_string16.h
+++ b/base/strings/nullable_string16.h
@@ -18,7 +18,6 @@
 class NullableString16 {
  public:
   NullableString16() : is_null_(true) { }
-  explicit NullableString16(bool is_null) : is_null_(is_null) { }
   NullableString16(const string16& string, bool is_null)
       : string_(string), is_null_(is_null) {
   }