Enforce SafetyMode for YouTube if prefs::kForceSafeSearch is on.

base/strings/string_util.h

Index: base/strings/string_util.h
diff --git a/base/strings/string_util.h b/base/strings/string_util.h
index a573e227df96f6d83ff9febd7695a8a75c854138..6cae42bbd4d4d7ad45dea90687be85ffd728e44f 100644
--- a/base/strings/string_util.h
+++ b/base/strings/string_util.h
@@ -461,6 +461,13 @@ BASE_EXPORT base::string16 JoinString(
     const std::vector<base::string16>& parts,
     const base::string16& separator);
 
+typedef std::vector<std::pair<std::string, std::string> > StringPairs;
+
+// Does the opposite of SplitStringIntoKeyValuePairs().
+BASE_EXPORT std::string JoinStringKeyValuePairs(const StringPairs& pairs,
+                                                char key_value_delimiter,
+                                                char key_value_pair_delimiter);
+
 // Replace $1-$2-$3..$9 in the format string with |a|-|b|-|c|..|i| respectively.
 // Additionally, any number of consecutive '$' characters is replaced by that
 // number less one. Eg $$->$, $$$->$$, etc. The offsets parameter here can be