--- a/media/libstagefright/binding/BitReader.cpp
+++ b/media/libstagefright/binding/BitReader.cpp
@@ -96,9 +96,15 @@ BitReader::ReadUTF8()
 }
 
 size_t
 BitReader::BitCount() const
 {
   return mSize * 8 - mBitReader->numBitsLeft();
 }
 
+size_t
+BitReader::BitsLeft() const
+{
+  return mBitReader->numBitsLeft();
+}
+
 } // namespace mp4_demuxer

--- a/media/libstagefright/binding/include/mp4_demuxer/BitReader.h
+++ b/media/libstagefright/binding/include/mp4_demuxer/BitReader.h
@@ -29,16 +29,18 @@ public:
   uint64_t ReadUTF8();
   // Read unsigned integer Exp-Golomb-coded.
   uint32_t ReadUE();
   // Read signed integer Exp-Golomb-coded.
   int32_t ReadSE();
 
   // Return the number of bits parsed so far;
   size_t BitCount() const;
+  // Return the number of bits left.
+  size_t BitsLeft() const;
 
 private:
   nsAutoPtr<stagefright::ABitReader> mBitReader;
   const size_t mSize;
 };
 
 } // namespace mp4_demuxer