Add VP9 raw bits reader

media/filters/vp9_raw_bits_reader.h

+// Copyright 2015 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 MEDIA_FILTERS_VP9_RAW_BITS_READER_
+#define MEDIA_FILTERS_VP9_RAW_BITS_READER_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class BitReader;
+
+// A class to read raw bits stream. See VP9 spec, "RAW-BITS DECODING" section
+// for detail.
+class MEDIA_EXPORT Vp9RawBitsReader {
+ public:
+  Vp9RawBitsReader();
+  ~Vp9RawBitsReader();
+
+  // |data| is the input buffer with |size| bytes.
+  void Initialize(const uint8_t* data, size_t size);
+
+  // Returns true if last reads don't go beyond the end of buffer.

[Pawel Osciak, 2015/08/05 07:08:57]

This is not only the last read, but any read since last Initialize().

Returns true if any of the reads since the last Initialize() call has gone
beyond the end of available data.

[kcwu, 2015/08/05 07:34:44]

Done.
As your suggestion, just s/any/none/

+  bool IsValid() const { return valid_; }
+
+  // Returns how many bytes were read since the last Initialize() call.
+  // Partial bytes will be counted as one byte. For example, it will return 1
+  // if 3 bits were read.
+  size_t GetBytesRead() const;
+
+  // Reads one bit.
+  // If the read goes beyond the end of buffer, the return value is undefined.
+  int ReadBit();
+
+  // Reads a literal with |bits| bits.
+  // If the read goes beyond the end of buffer, the return value is undefined.
+  int ReadLiteral(int bits);
+
+  // Reads a signed literal with |bits| bits (not including the sign bit).
+  // If the read goes beyond the end of buffer, the return value is undefined.
+  int ReadSignedLiteral(int bits);
+
+ private:
+  scoped_ptr<BitReader> reader_;
+
+  // Indicates error status that the caller reads beyond the end of input

[Pawel Osciak, 2015/08/05 07:08:57]

This comment needs an update.

[kcwu, 2015/08/05 07:34:44]

Done.

+  // buffer.
+  bool valid_;
+
+  DISALLOW_COPY_AND_ASSIGN(Vp9RawBitsReader);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_VP9_RAW_BITS_READER_