Parse ELNG box in MP4 container

media/formats/mp4/box_reader.cc

Index: media/formats/mp4/box_reader.cc
diff --git a/media/formats/mp4/box_reader.cc b/media/formats/mp4/box_reader.cc
index 91e406d227f07ad0ca4f22fabd7946a501721fd8..f3ed5e54448658ba8a5841428acd0743c9bd7bfd 100644
--- a/media/formats/mp4/box_reader.cc
+++ b/media/formats/mp4/box_reader.cc
@@ -67,6 +67,19 @@ bool BufferReader::ReadVec(std::vector<uint8_t>* vec, uint64_t count) {
   return true;
 }
 
+bool BufferReader::ReadString(std::string* v) {
+  RCHECK(v);
+  *v = "";
+  uint8_t c = 0;
+  while (Read1(&c) && c != 0) {
+    v->push_back(c);
+  }
+  // Return error if we didn't find the terminating zero character.
+  if (c != 0)
+    return false;
+  return true;
+}
+
 bool BufferReader::SkipBytes(uint64_t bytes) {
   RCHECK(HasBytes(bytes));
   pos_ += bytes;