Split up quic_frames.{h,cc} into files for each frame type.

net/quic/core/frames/quic_window_update_frame.cc

+// Copyright (c) 2016 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 "net/quic/core/frames/quic_window_update_frame.h"
+
+using std::ostream;
+
+namespace net {
+
+QuicWindowUpdateFrame::QuicWindowUpdateFrame(QuicStreamId stream_id,
+                                             QuicStreamOffset byte_offset)
+    : stream_id(stream_id), byte_offset(byte_offset) {}
+
+ostream& operator<<(ostream& os,
+                    const QuicWindowUpdateFrame& window_update_frame) {
+  os << "{ stream_id: " << window_update_frame.stream_id
+     << ", byte_offset: " << window_update_frame.byte_offset << " }\n";
+  return os;
+}
+
+}  // namespace net