Fix handling of Unicode BOMs in JSONReader.

base/json/json_reader.cc

 // Copyright (c) 2012 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 "base/json/json_reader.h"
 
 #include "base/float_util.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stringprintf.h"
@@ skipping 145 matching lines @@
     return NULL;
   }
 
   start_pos_ = json.data();
   end_pos_ = start_pos_ + json.size();
 
   // When the input JSON string starts with a UTF-8 Byte-Order-Mark (U+FEFF)
   // or <0xEF 0xBB 0xBF>, advance the start position to avoid the
   // JSONReader::BuildValue() function from mis-treating a Unicode BOM as an
   // invalid character and returning NULL.
-  if (json.size() >= 3 && start_pos_[0] == 0xEF &&
-      start_pos_[1] == 0xBB && start_pos_[2] == 0xBF) {
+  if (json.size() >= 3 && static_cast<uint8>(start_pos_[0]) == 0xEF &&
+      static_cast<uint8>(start_pos_[1]) == 0xBB &&
+      static_cast<uint8>(start_pos_[2]) == 0xBF) {
     start_pos_ += 3;
   }
 
   json_pos_ = start_pos_;
   allow_trailing_comma_ = allow_trailing_comma;
   stack_depth_ = 0;
   error_code_ = JSON_NO_ERROR;
 
   scoped_ptr<Value> root(BuildValue(check_root));
   if (root.get()) {
@@ skipping 540 matching lines @@
       ++column_number;
     }
   }
 
   error_line_ = line_number;
   error_col_ = column_number;
   error_code_ = error;
 }
 
 }  // namespace base