PaymentApp: Add a interface to query all payment app manifests.

content/public/browser/payment_app_context.h

+// Copyright 2016 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 CONTENT_PUBLIC_BROWSER_PAYMENT_APP_CONTEXT_H_
+#define CONTENT_PUBLIC_BROWSER_PAYMENT_APP_CONTEXT_H_
+
+#include <utility>
+#include <vector>
+
+#include "base/callback_forward.h"
+
+namespace content {
+
+class PaymentAppContext {
+ public:
+  // The ManifestWithID is a pair of the service worker registration id and
+  // the payment app manifest data associated with it.
+  using ManifestWithID =
+      std::pair<int64_t, payments::mojom::PaymentAppManifestPtr>;
+  using Manifests = std::vector<ManifestWithID>;
+  using GetAllManifestsCallback = base::Callback<void(Manifests)>;
+
+  virtual void GetAllManifests(const GetAllManifestsCallback& callback) = 0;
+};

[please use gerrit instead, 2016/12/14 16:50:06]

Need a destructor:

"An interface class can never be directly instantiated because of the pure
virtual method(s) it declares. To make sure all implementations of the interface
can be destroyed correctly, the interface must also declare a virtual destructor
(in an exception to the first rule, this should not be pure). See Stroustrup,
The C++ Programming Language, 3rd edition, section 12.4 for details."

https://google.github.io/styleguide/cppguide.html#Interfaces

[zino, 2016/12/14 17:20:19]

Done.

+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_PAYMENT_APP_CONTEXT_H_