media: Add ProvisionFetcher mojo interface and implementation.

content/browser/media/android/provision_fetcher_impl.h

+// 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.
+
+#ifndef CONTENT_BROWSER_MEDIA_ANDROID_PROVISION_FETCHER_IMPL_H_
+#define CONTENT_BROWSER_MEDIA_ANDROID_PROVISION_FETCHER_IMPL_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/android/provision_fetcher_factory.h"
+#include "media/base/android/provision_fetcher.h"
+#include "media/mojo/interfaces/provision_fetcher.mojom.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace content {
+
+class RenderFrameHost;
+
+// An media::interfaces::ProvisionFetcher implementation based on
+// media::ProvisionFetcher.
+class ProvisionFetcherImpl : public media::interfaces::ProvisionFetcher {
+ public:
+  static void Create(
+      RenderFrameHost* render_frame_host,
+      mojo::InterfaceRequest<media::interfaces::ProvisionFetcher> request);
+
+  ProvisionFetcherImpl(scoped_ptr<media::ProvisionFetcher> provision_fetcher,
+                       mojo::InterfaceRequest<ProvisionFetcher> request);
+  ~ProvisionFetcherImpl() override;
+
+  // media::interfaces::ProvisionFetcher implementation.
+  void Retrieve(const mojo::String& default_url,
+                const mojo::String& request_data,
+                const RetrieveCallback& callback) final;
+
+ private:
+  // Callback for media::ProvisionFetcher::Retrieve().
+  void OnResponse(const RetrieveCallback& callback,
+                  bool success,
+                  const std::string& response);
+
+  mojo::StrongBinding<media::interfaces::ProvisionFetcher> binding_;
+  scoped_ptr<media::ProvisionFetcher> provision_fetcher_;

[xhwang, 2015/11/20 22:28:34]

rockot:

We have this "sandwich" model in many places to support some functionality that
is implemented in one process but used in another process. In this particular
case, we have:

media::ProvisionFetcher (in Browser) <-
media::interfaces::ProvisionFetcher <-
IPC/Mojo <-
media::interfaces::ProvisionFetcherPtr <-
media::ProvisionFetcher (in  GPU)

It's working well but I feel we have too many boilerplate code. Is there any way
to simply this model? 

+
+  base::WeakPtrFactory<ProvisionFetcherImpl> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProvisionFetcherImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEDIA_ANDROID_PROVISION_FETCHER_IMPL_H_