downloads: break downloads.js into more classes/files.

chrome/browser/resources/downloads/externs.js

Index: chrome/browser/resources/downloads/externs.js
diff --git a/chrome/browser/resources/downloads/externs.js b/chrome/browser/resources/downloads/externs.js
new file mode 100644
index 0000000000000000000000000000000000000000..4b94b85104b44dfa8a6b058130f2b71ae9293cfa
--- /dev/null
+++ b/chrome/browser/resources/downloads/externs.js
@@ -0,0 +1,37 @@
+// 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.
+
+/**
+ * @fileoverview Externs for objects sent from C++ to JS for chrome://downloads.
+ * @externs
+ */
+
+var downloads = {};
+
+/**
+ * The type of the download object. The definition is based on
+ * chrome/browser/ui/webui/downloads_dom_handler.cc:CreateDownloadItemValue()
+ * @typedef {{by_ext_id: (string|undefined),
+ *            by_ext_name: (string|undefined),
+ *            danger_type: (string|undefined),
+ *            date_string: string,
+ *            file_externally_removed: boolean,
+ *            file_name: string,
+ *            file_path: string,
+ *            file_url: string,
+ *            id: string,
+ *            last_reason_text: (string|undefined),
+ *            otr: boolean,
+ *            percent: (number|undefined),
+ *            progress_status_text: (string|undefined),
+ *            received: (number|undefined),
+ *            resume: boolean,
+ *            retry: boolean,
+ *            since_string: string,
+ *            started: number,
+ *            state: string,
+ *            total: number,
+ *            url: string}}
+ */
+downloads.Data;