Get media feed items from a schema org entity and validate against spec.

Not done in this CL, but intended in the future:
* Genre should be able to store multiple values.
* TV episode images.
* Play next episode.
* Storage of the media feed items in media history.
* End to end testing using a full JSON example.

Change-Id: Ib4c6d9421c61ed98426aabc5b6056f0437195782
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2112957Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Sam Bowen <sgbowen@google.com>
Cr-Commit-Position: refs/heads/master@{#756355}

chrome/browser/BUILD.gn

@@ -682,6 +682,8 @@ jumbo_static_library("browser") {
     "media/cast_remoting_connector.h",
     "media/feeds/media_feeds_contents_observer.cc",
     "media/feeds/media_feeds_contents_observer.h",
+    "media/feeds/media_feeds_converter.cc",
+    "media/feeds/media_feeds_converter.h",
     "media/feeds/media_feeds_fetcher.cc",
     "media/feeds/media_feeds_fetcher.h",
     "media/feeds/media_feeds_service.cc",

chrome/browser/media/feeds/media_feeds_converter.h

+// Copyright 2020 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.
+
+#ifndef CHROME_BROWSER_MEDIA_FEEDS_MEDIA_FEEDS_CONVERTER_H_
+#define CHROME_BROWSER_MEDIA_FEEDS_MEDIA_FEEDS_CONVERTER_H_
+
+#include "chrome/browser/media/feeds/media_feeds_store.mojom.h"
+#include "components/schema_org/common/improved_metadata.mojom.h"
+
+namespace media_feeds {
+
+// Given a schema_org entity of type CompleteDataFeed, converts all items
+// contained in the feed to MediaFeedItemPtr type and returns them in a vector.
+// The feed should be valid according to https://wicg.github.io/media-feeds/. If
+// not, GetMediaFeeds returns an empty result. If the feed is valid, but some of
+// its feed items are not, GetMediaFeeds excludes the invalid feed items from
+// the returned result.
+base::Optional<std::vector<mojom::MediaFeedItemPtr>> GetMediaFeeds(
+    schema_org::improved::mojom::EntityPtr schema_org_entity);
+
+}  // namespace media_feeds
+
+#endif  // CHROME_BROWSER_MEDIA_FEEDS_MEDIA_FEEDS_CONVERTER_H_

chrome/test/BUILD.gn

@@ -3158,6 +3158,7 @@ test("unit_tests") {
     "../browser/mac/keystone_glue_unittest.mm",
     "../browser/media/android/router/media_router_android_unittest.cc",
     "../browser/media/cast_mirroring_service_host_unittest.cc",
+    "../browser/media/feeds/media_feeds_converter_unittest.cc",
     "../browser/media/feeds/media_feeds_fetcher_unittest.cc",
     "../browser/media/feeds/media_feeds_service_unittest.cc",
     "../browser/media/history/media_history_keyed_service_unittest.cc",