Error diagnostics for Blacklist IO...

chrome/tools/pbl_tool/pbl_tool.cc

 // 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.
 
 // This tool manages privacy blacklists. Primarily for loading a text
 // blacklist into the binary aggregate blacklist.
 #include <iostream>
 
 #include "base/process_util.h"
 #include "base/string_util.h"
@@ skipping 26 matching lines @@
 int IMAIN(int argc, ICHAR* argv[]) {
   base::EnableTerminationOnHeapCorruption();
 
   if (argc < 3)
     return PrintUsage(argc, argv);
 
   BlacklistIO io;
   for (int current = 1; current < argc-1; ++current) {
     FilePath input(argv[current]);
     if (!io.Read(input)) {
-      ICERR << "Error reading input file " << argv[current] << "\n";
+      ICERR << "Error reading " << argv[current] << ":\n"
+            << io.last_error() << "\n";
       return -1;
     }
   }
 
   FilePath output(argv[argc-1]);
   if (!io.Write(output))
-    ICERR << "Error writing output file " << argv[2] << "\n";
+    ICERR << "Error writing " << argv[2] << ":\n" << io.last_error() << "\n";
 
   return 0;
 }