Refactor getInstalledRelatedApps code and add manifest logic and tests.

content/renderer/installedapp/related_apps_fetcher.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 "content/renderer/installedapp/related_apps_fetcher.h"
+
+#include "base/bind.h"
+#include "content/public/common/manifest.h"
+#include "content/renderer/manifest/manifest_debug_info.h"
+#include "content/renderer/manifest/manifest_manager.h"
+#include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/platform/modules/installedapp/WebRelatedApplication.h"
+
+namespace content {
+
+RelatedAppsFetcher::RelatedAppsFetcher(ManifestManager* manifest_manager)
+    : manifest_manager_(manifest_manager) {}
+
+RelatedAppsFetcher::~RelatedAppsFetcher() {}
+
+void RelatedAppsFetcher::getManifestRelatedApplications(
+    std::unique_ptr<blink::WebCallbacks<
+        const blink::WebVector<blink::WebRelatedApplication>&,
+        void>> callbacks) {
+  manifest_manager_->GetManifest(
+      base::Bind(&RelatedAppsFetcher::OnGetManifestForRelatedApplications,
+                 base::Unretained(this), base::Passed(&callbacks)));
+}
+
+void RelatedAppsFetcher::OnGetManifestForRelatedApplications(
+    std::unique_ptr<blink::WebCallbacks<
+        const blink::WebVector<blink::WebRelatedApplication>&,
+        void>> callbacks,
+    const GURL& /*url*/,
+    const Manifest& manifest,
+    const ManifestDebugInfo& /*manifest_debug_info*/) {
+  std::vector<blink::WebRelatedApplication> related_apps;
+  for (const auto& relatedApplication : manifest.related_applications) {
+    blink::WebRelatedApplication webRelatedApplication;
+    webRelatedApplication.platform =
+        blink::WebString::fromUTF16(relatedApplication.platform.string());

[esprehn, 2017/02/15 01:56:50]

This doesn't preserve the nullability, WebString can be null, but you're making
a null platform into an empty string, is that right?

[Matt Giuca, 2017/02/15 07:55:34]

Done. (WebString::fromUTF16 has an overload that takes a NullableString16, so
just use that.)

Note: This can't be tested just yet (because the code currently drops this data
on the floor) -- the next CL will pass it to Mojo and it will be tested there (I
have already verified that the tests in the follow-up CL catch this).

+    webRelatedApplication.id =
+        blink::WebString::fromUTF16(relatedApplication.id.string());

[esprehn, 2017/02/15 01:56:50]

ditto

[Matt Giuca, 2017/02/15 07:55:34]

Done.

+    webRelatedApplication.url =
+        blink::WebString::fromUTF8(relatedApplication.url.spec());

[Matt Giuca, 2017/02/15 07:55:34]

url doesn't have a concept of null, but I felt it was right to translate
emptiness into null (rather than the empty string).

+    related_apps.push_back(std::move(webRelatedApplication));
+  }
+  callbacks->onSuccess(std::move(related_apps));
+}
+
+}  // namespace content