Introduces QuicStreamSequencerBufferInterface with one implementation. Refactor, no behavior change.

net/quic/test_tools/quic_stream_sequencer_peer.cc

Index: net/quic/test_tools/quic_stream_sequencer_peer.cc
diff --git a/net/quic/test_tools/quic_stream_sequencer_peer.cc b/net/quic/test_tools/quic_stream_sequencer_peer.cc
index 0d2c61b11abdc3412985bc46bc7bfc81a7599d10..fea4579cbcb21498206e47042ee54a05de7bd409 100644
--- a/net/quic/test_tools/quic_stream_sequencer_peer.cc
+++ b/net/quic/test_tools/quic_stream_sequencer_peer.cc
@@ -13,20 +13,19 @@ namespace net {
 namespace test {
 
 // static
-size_t QuicStreamSequencerPeer::GetNumBufferedFrames(
+size_t QuicStreamSequencerPeer::GetNumBufferedBytes(
     QuicStreamSequencer* sequencer) {
-  return sequencer->buffered_frames_.size();
+  return sequencer->buffered_frames_->BytesBuffered();
 }
 
 // static
 bool QuicStreamSequencerPeer::FrameOverlapsBufferedData(
-    QuicStreamSequencer* sequencer,
+    QuicFrameList* buffer,
     const QuicStreamFrame& frame) {
   list<QuicFrameList::FrameData>::iterator it =
-      sequencer->buffered_frames_.FindInsertionPoint(frame.offset,
-                                                     frame.data.length());
-  return sequencer->buffered_frames_.FrameOverlapsBufferedData(
-      frame.offset, frame.data.length(), it);
+      buffer->FindInsertionPoint(frame.offset, frame.data.length());
+  return buffer->FrameOverlapsBufferedData(frame.offset, frame.data.length(),
+                                           it);
 }
 
 // static