Add an initial implementation of the downloads MD settings page.

chrome/browser/resources/settings/downloads_page/downloads_page.js

Index: chrome/browser/resources/settings/downloads_page/downloads_page.js
diff --git a/chrome/browser/resources/settings/downloads_page/downloads_page.js b/chrome/browser/resources/settings/downloads_page/downloads_page.js
new file mode 100644
index 0000000000000000000000000000000000000000..684e5f6f0cbfbfb523e516c661c7927a742c6617
--- /dev/null
+++ b/chrome/browser/resources/settings/downloads_page/downloads_page.js
@@ -0,0 +1,38 @@
+// 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
+ * 'cr-settings-downloads-page' is the settings page containing all downloads

[michaelpg, 2015/03/08 05:37:36]

nit: let's not claim this contains ALL the downloads settings.

[Oren Blasberg, 2015/03/09 21:05:05]

Why not? Doesn't it contain them?

[michaelpg, 2015/03/09 21:24:08]

For example it's missing auto-open settings, which you can set in the downloads
bar (and then a button to "clear auto-opening settings" appears in
chrome://settings).

Moreover we'd have to update this every time we add a setting that isn't on this
page or remove a setting from this page... it just seems like an unnecessary
claim.

But it's just a nit.

[Oren Blasberg, 2015/03/09 21:39:13]

Done.

+ * settings.
+ *
+ * Example:
+ *
+ *    <core-animated-pages>
+ *      <cr-settings-downloads-page></cr-settings-downloads-page>
+ *      ... other pages ...
+ *    </core-animated-pages>
+ *
+ * @group Chrome Settings Elements
+ * @element cr-settings-downloads-page
+ */
+Polymer('cr-settings-downloads-page', {
+  publish: {
+    /**
+     * Preferences state.
+     *
+     * @attribute prefs
+     * @type CrSettingsPrefsElement
+     * @default null
+     */
+    prefs: null

[michaelpg, 2015/03/08 05:37:36]

nit: add trailing comma. You may already know this, but I think this is
suggested mainly to make git history clearer -- when someone adds another
property after this, they'll be "blamed" for this line as well, just for
appending a comma.

TL;DR: if something catches fire I want to make sure I can point my pitchfork in
your direction

[Oren Blasberg, 2015/03/09 21:05:05]

Done.

+  },
+
+  selectDownloadLocation: function() {
+    // TODO(orenb): Communicate with the C++ to actually display a folder
+    // picker.
+    this.$.downloadsPath.value = '/Downloads';
+    this.prefs.settings.downloads.downloadLocation = '/Downloads';
+  },
+});