Add a histogram for size of the memory used by redirect chain.

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 <iosfwd>
 #include <string>
 
@@ skipping 344 matching lines @@
   // who return references but don't have anything to return in some cases.
   // This function may be called from any thread.
   static const GURL& EmptyGURL();
 
   // Returns the inner URL of a nested URL [currently only non-null for
   // filesystem: URLs].
   const GURL* inner_url() const {
     return inner_url_.get();
   }
 
+  // Returns approximate size of the memory taken by the instance.
+  size_t Bytesize() const;
+
  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>
@@ skipping 22 matching lines @@
   // Used for nested schemes [currently only filesystem:].
   scoped_ptr<GURL> inner_url_;
 
   // TODO bug 684583: Add encoding for query params.
 };
 
 // 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_