HexStringToUInt64 should fail for negative input

base/strings/string_number_conversions.h

 // 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.
 
 #ifndef BASE_STRINGS_STRING_NUMBER_CONVERSIONS_H_
 #define BASE_STRINGS_STRING_NUMBER_CONVERSIONS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 32 matching lines @@
 
 // DoubleToString converts the double to a string format that ignores the
 // locale. If you want to use locale specific formatting, use ICU.
 BASE_EXPORT std::string DoubleToString(double value);
 
 // String -> number conversions ------------------------------------------------
 
 // Perform a best-effort conversion of the input string to a numeric type,
 // setting |*output| to the result of the conversion.  Returns true for
 // "perfect" conversions; returns false in the following cases:
-//  - Overflow/underflow.  |*output| will be set to the maximum value supported
+//  - Overflow. |*output| will be set to the maximum value supported
+//    by the data type.
+//  - Underflow. |*output| will be set to the minimum value supported
 //    by the data type.
 //  - Trailing characters in the string after parsing the number.  |*output|
 //    will be set to the value of the number that was parsed.
 //  - Leading whitespace in the string before parsing the number. |*output| will
 //    be set to the value of the number that was parsed.
 //  - No characters parseable as a number at the beginning of the string.
 //    |*output| will be set to 0.
 //  - Empty string.  |*output| will be set to 0.
 BASE_EXPORT bool StringToInt(const StringPiece& input, int* output);
 BASE_EXPORT bool StringToInt(const StringPiece16& input, int* output);
@@ skipping 47 matching lines @@
 // Similar to the previous functions, except that output is a vector of bytes.
 // |*output| will contain as many bytes as were successfully parsed prior to the
 // error.  There is no overflow, but input.size() must be evenly divisible by 2.
 // Leading 0x or +/- are not allowed.
 BASE_EXPORT bool HexStringToBytes(const std::string& input,
                                   std::vector<uint8>* output);
 
 }  // namespace base
 
 #endif  // BASE_STRINGS_STRING_NUMBER_CONVERSIONS_H_