Add a Model to the download component.

components/download/internal/entry.cc

+// Copyright 2017 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 "components/download/internal/entry.h"
+
+namespace download {
+
+Entry::Entry() : client(DownloadClient::INVALID), state(State::NEW) {}

[Peter Beverloo, 2017/05/10 12:44:44]

something to consider: you can initialize scalars in the header file these days.
Adds more explicit initial-state documentation to the header, and allows another
fancy `= default;` in this file.

[David Trainor- moved to gerrit, 2017/05/15 15:59:51]

Done.  Sometimes I keep it in the cc file so I can initialize everything in one
place.  But so far these are the only things I have to initialize, so that works
:).

+Entry::Entry(const Entry& other) = default;
+Entry::~Entry() = default;
+
+}  // namespace download