Fix: Adding list of supported codecs for MP4 containers

base/strings/string_util.h

Index: base/strings/string_util.h
diff --git a/base/strings/string_util.h b/base/strings/string_util.h
index 473deaebe87d5bca7556418531856ada2c629c61..3b1c06a68faf7c2b6c1ede3d703d1af54ec6cc75 100644
--- a/base/strings/string_util.h
+++ b/base/strings/string_util.h
@@ -259,6 +259,8 @@ BASE_EXPORT bool IsStringUTF8(const std::string& str);
 BASE_EXPORT bool IsStringASCII(const base::StringPiece& str);
 BASE_EXPORT bool IsStringASCII(const base::string16& str);
 
+BASE_EXPORT bool IsUpperCaseHexNumber(const std::string& number);
+
 // Converts the elements of the given string.  This version uses a pointer to
 // clearly differentiate it from the non-pointer variant.
 template <class str> inline void StringToLowerASCII(str* s) {
@@ -352,6 +354,11 @@ inline bool IsHexDigit(Char c) {
 }
 
 template <typename Char>
+inline bool IsUpperCaseHexDigit(Char c) {
+  return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F');
+}
+
+template <typename Char>
 inline Char HexDigitToInt(Char c) {
   DCHECK(IsHexDigit(c));
   if (c >= '0' && c <= '9')