Error diagnostics for Blacklist IO...

chrome/browser/privacy_blacklist/blacklist_io.h

 // Copyright (c) 2009 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 CHROME_BROWSER_PRIVACY_BLACKLIST_BLACKLIST_IO_H_
 #define CHROME_BROWSER_PRIVACY_BLACKLIST_BLACKLIST_IO_H_
 
 #include <list>
 
+#include "base/string16.h"
 #include "chrome/browser/privacy_blacklist/blacklist.h"
 
 class FilePath;
 
 // Helper class to keep state while reading multiple text blacklists to
 // produce a single binary blacklist used by the Blacklist constructor.
 class BlacklistIO {
  public:
   BlacklistIO();
   ~BlacklistIO();
 
   // Reads a text blacklist, as downloaded from the blacklist provider.
   bool Read(const FilePath& path);
 
   // Writes a binary blacklist with aggregated entries for all read blacklists.
   bool Write(const FilePath& path);
 
+  // Returns the text of the last occuring error. An empty string is returned
+  // if no such error happened.
+  const string16& last_error() const {
+    return last_error_;
+  }
+
  private:
   // Introspection functions, for testing purposes.
   const std::list<Blacklist::Entry*>& blacklist() const {
     return blacklist_;
   }
   const std::list<Blacklist::Provider*>& providers() const {
     return providers_;
   }
 
   std::list<Blacklist::Entry*> blacklist_;
   std::list<Blacklist::Provider*> providers_;
+  string16 last_error_;  // Stores text of last error, empty if N/A.
 
   FRIEND_TEST(BlacklistIOTest, Generic);
   FRIEND_TEST(BlacklistIOTest, Combine);
   DISALLOW_COPY_AND_ASSIGN(BlacklistIO);
 };
 
 #endif  // CHROME_BROWSER_PRIVACY_BLACKLIST_BLACKLIST_IO_H_