Introduced ChunkedByteBuffer class which will be needed by next speech recognition CLs.

content/browser/speech/chunked_byte_buffer.cc

+// Copyright (c) 2012 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.
+
+#include "content/browser/speech/chunked_byte_buffer.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+namespace speech {
+
+const int ChunkedByteBuffer::kLengthFieldSize = sizeof(uint32);
+
+ChunkedByteBuffer::ChunkedByteBuffer() {
+}
+
+ChunkedByteBuffer::~ChunkedByteBuffer() {
+}
+
+void ChunkedByteBuffer::Append(const uint8* start, size_t length) {
+  buffer_.reserve(buffer_.size() + length);

[Satish, 2012/04/23 11:01:44]

I haven't verified it but can we use
  buffer_.insert(buffer_.end(), start, start + length);
?

[Primiano Tucci (use gerrit), 2012/04/23 17:13:57]

Done.

+  std::copy(start, start+length, std::back_inserter(buffer_));
+}
+
+void ChunkedByteBuffer::Append(const std::string& string) {
+  Append(reinterpret_cast<const uint8*>(string.data()), string.size());
+}
+
+bool ChunkedByteBuffer::CanReadChunk(size_t* chunk_length) const {
+  const size_t buffer_size = buffer_.size();
+  if (buffer_size < kLengthFieldSize)
+    return false;
+
+  COMPILE_ASSERT(sizeof(size_t) >= kLengthFieldSize,

[Satish, 2012/04/23 11:01:44]

move this outside to line 13

[Primiano Tucci (use gerrit), 2012/04/23 17:13:57]

Done.

+                 ChunkedByteBufferNotSupportedOnThisArchitecture);
+
+  size_t next_chunk_length = ReadBigEndian32(&buffer_[0]);
+  const size_t bytes_required_to_read_next_chunk = kLengthFieldSize +
+                                                   next_chunk_length;
+  if (buffer_size < bytes_required_to_read_next_chunk)
+    return false;
+
+  if (chunk_length != NULL)
+    *chunk_length = next_chunk_length;
+  return true;
+}
+
+bool ChunkedByteBuffer::CanReadChunk() const {
+  return CanReadChunk(NULL);
+}
+
+bool ChunkedByteBuffer::ReadChunk(const uint8** start_ptr,
+                                  size_t* length) const {
+  DCHECK(start_ptr != NULL);
+  DCHECK(length != NULL);
+  const bool can_read_chunk = CanReadChunk(length);
+  if (!can_read_chunk)
+    return false;
+  *start_ptr = &buffer_[kLengthFieldSize];
+  return true;
+}
+
+void ChunkedByteBuffer::RemoveChunk() {
+  size_t chunk_length;
+  const bool can_read_chunk = CanReadChunk(&chunk_length);
+
+  if (!can_read_chunk) {
+    NOTREACHED();
+    return;
+  }
+  buffer_.erase(buffer_.begin(),
+                buffer_.begin() + kLengthFieldSize + chunk_length);
+}
+
+void ChunkedByteBuffer::Clear() {
+  buffer_.clear();
+}
+
+uint32 ChunkedByteBuffer::ReadBigEndian32(const uint8* buffer) {
+  return (static_cast<uint32>(buffer[3])) |
+         (static_cast<uint32>(buffer[2]) <<  8) |
+         (static_cast<uint32>(buffer[1]) << 16) |
+         (static_cast<uint32>(buffer[0]) << 24);
+}
+
+}  // namespace speech