Upstream "nsurl_util.{h,mm}" from Chrome on iOS repository.

net/base/escape.h

Index: net/base/escape.h
diff --git a/net/base/escape.h b/net/base/escape.h
index 6c92333ba3db6582cf7f68c8c06e914056787c6d..9722060b4e21ca3e1b447478cbafe70d84db80f4 100644
--- a/net/base/escape.h
+++ b/net/base/escape.h
@@ -30,6 +30,10 @@ NET_EXPORT std::string EscapeQueryParamValue(const std::string& text,
 // encoding the string.  If this conversion fails, we return false.
 NET_EXPORT std::string EscapePath(const std::string& path);
 
+// Escapes characters as per expectations of NSURL. This includes:
+// non-printable, non-7bit, and (including space)  "#%<>[\]^`{|}
+NET_EXPORT std::string EscapeNSURLPrecursor(const std::string& precursor);

[mmenke, 2014/12/03 15:30:12]

optional:  Suggest surrounding this in #ifdef OS_MACOSX (That's define on iOS
and OSX, right?).  Not because compiling it elsewhere is the end of the world,
but just to indicate there's no reason to use it eslewhere.

[erikchen, 2014/12/03 18:14:01]

Done.

+
 // Escapes application/x-www-form-urlencoded content.  This includes:
 // non-printable, non-7bit, and (including space)  ?>=<;+'&%$#"![\]^`{|}
 // Space is escaped as + (if use_plus is true) and other special characters