Fix: Adding list of supported codecs for MP4 containers

base/strings/string_util.cc

Index: base/strings/string_util.cc
diff --git a/base/strings/string_util.cc b/base/strings/string_util.cc
index e514ac1a6327416925969dd78ad5a730663ab2ea..9017741b8da80fbec66d12f3ee37b592775c1ccf 100644
--- a/base/strings/string_util.cc
+++ b/base/strings/string_util.cc
@@ -344,6 +344,18 @@ bool IsStringASCII(const base::string16& str) {
   return DoIsStringASCII(str);
 }
 
+bool IsUpperCaseHexNumber(const std::string& number) {
+  if (!number.length())
+    return false;
+
+  for (size_t i = 0; i < number.length(); ++i) {
+    if (!IsUpperCaseHexDigit(number.at(i)))
+      return false;
+  }
+
+  return true;
+}
+
 bool IsStringUTF8(const std::string& str) {
   const char *src = str.data();
   int32 src_len = static_cast<int32>(str.length());