Reduce string copies in GURL creation

url/gurl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef URL_GURL_H_
 #define URL_GURL_H_
 
 #include <stddef.h>
 
 #include <iosfwd>
@@ skipping 38 matching lines @@
   typedef url::StringPieceReplacements<base::string16> ReplacementsW;
 
   // Creates an empty, invalid URL.
   GURL();
 
   // Copy construction is relatively inexpensive, with most of the time going
   // to reallocating the string. It does not re-parse.
   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
   // information associated with the URL, which must be correct and consistent.
   GURL(const char* canonical_spec,
        size_t canonical_spec_len,
        const url::Parsed& parsed,
        bool is_valid);
   // Notice that we take the canonical_spec by value so that we can convert
   // from WebURL without copying the string. When we call this constructor
@@ skipping 327 matching lines @@
  private:
   // Variant of the string parsing constructor that allows the caller to elect
   // retain trailing whitespace, if any, on the passed URL spec, but only if
   // the scheme is one that allows trailing whitespace. The primary use-case is
   // for data: URLs. In most cases, you want to use the single parameter
   // constructor above.
   enum RetainWhiteSpaceSelector { RETAIN_TRAILING_PATH_WHITEPACE };
   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();
 
   // Returns the substring of the input identified by the given component.
   std::string ComponentString(const url::Component& comp) const {
     if (comp.len <= 0)
       return std::string();
     return std::string(spec_, comp.begin, comp.len);
   }
   base::StringPiece ComponentStringPiece(const url::Component& comp) const {
@@ skipping 14 matching lines @@
   url::Parsed parsed_;
 
   // Used for nested schemes [currently only filesystem:].
   scoped_ptr<GURL> inner_url_;
 };
 
 // Stream operator so GURL can be used in assertion statements.
 URL_EXPORT std::ostream& operator<<(std::ostream& out, const GURL& url);
 
 #endif  // URL_GURL_H_