Reduce string copies in GURL creation

url/gurl.h

Index: url/gurl.h
diff --git a/url/gurl.h b/url/gurl.h
index b49d2fdb1c618ff20482eaf702949f86a9c112b1..6af2baccea7549f989d11f0ebc8d7d16325deaac 100644
--- a/url/gurl.h
+++ b/url/gurl.h
@@ -56,8 +56,8 @@ class URL_EXPORT GURL {
   GURL(const GURL& other);
 
   // The strings to this contructor should be UTF-8 / UTF-16.
-  explicit GURL(const std::string& url_string);
-  explicit GURL(const base::string16& url_string);
+  explicit GURL(base::StringPiece url_string);
+  explicit GURL(base::StringPiece16 url_string);
 
   // Constructor for URLs that have already been parsed and canonicalized. This
   // is used for conversions from KURL, for example. The caller must supply all
@@ -405,7 +405,8 @@ class URL_EXPORT GURL {
   GURL(const std::string& url_string, RetainWhiteSpaceSelector);
 
   template<typename STR>
-  void InitCanonical(const STR& input_spec, bool trim_path_end);
+  void InitCanonical(base::BasicStringPiece<STR> input_spec,
+                     bool trim_path_end);
 
   void InitializeFromCanonicalSpec();