Don't unescape backslashes in URLs, since these will be converted to slashes...

net/base/escape.cc

 // Copyright (c) 2010 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.
 
 #include <algorithm>
 
 #include "net/base/escape.h"
 
 #include "base/i18n/icu_string_conversions.h"
 #include "base/logging.h"
@@ skipping 53 matching lines @@
   return escaped;
 }
 
 // Contains nonzero when the corresponding character is unescapable for normal
 // URLs. These characters are the ones that may change the parsing of a URL, so
 // we don't want to unescape them sometimes. In many case we won't want to
 // unescape spaces, but that is controlled by parameters to Unescape*.
 //
 // The basic rule is that we can't unescape anything that would changing parsing
 // like # or ?. We also can't unescape &, =, or + since that could be part of a
-// query and that could change the server's parsing of the query.
+// query and that could change the server's parsing of the query. Nor can we
+// unescape \ since googleurl will convert it to a /.
 //
 // Lastly, we can't unescape anything that doesn't have a canonical
 // representation in a URL. This means that unescaping will change the URL, and
 // you could get different behavior if you copy and paste the URL, or press
 // enter in the URL bar. The list of characters that fall into this category
 // are the ones labeled PASS (allow either escaped or unescaped) in the big
 // lookup table at the top of googleurl/src/url_canon_path.cc
 const char kUrlUnescape[128] = {
 //   NULL, control chars...
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 //  ' ' !  "  #  $  %  &  '  (  )  *  +  ,  -  .  /
      0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0,
 //   0  1  2  3  4  5  6  7  8  9  :  ;  <  =  >  ?
      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0,
 //   @  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O
      0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 //   P  Q  R  S  T  U  V  W  X  Y  Z  [  \  ]  ^  _
-     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1,
+     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1,
 //   `  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o
      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 //   p  q  r  s  t  u  v  w  x  y  z  {  |  }  ~  <NBSP>
      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0
 };
 
 template<typename STR>
 STR UnescapeURLImpl(const STR& escaped_text,
                     UnescapeRule::Type rules,
                     size_t* offset_for_adjustment) {
@@ skipping 252 matching lines @@
         if (text.find(ampersand_chars[i], index) == index) {
           text.replace(iter, iter + ampersand_chars[i].length(),
                        1, kEscapeToChars[i].replacement);
           break;
         }
       }
     }
   }
   return text;
 }