[Presentation API] (alternative) 1-UA: send message between controller and receiver page

content/renderer/presentation/presentation_connection_proxy.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_RENDERER_PRESENTATION_PRESENTATION_CONNECTION_PROXY_H_
+#define CONTENT_RENDERER_PRESENTATION_PRESENTATION_CONNECTION_PROXY_H_
+
+#include "base/callback.h"
+#include "mojo/public/cpp/bindings/binding.h"
+#include "third_party/WebKit/public/platform/modules/presentation/WebPresentationConnection.h"
+#include "third_party/WebKit/public/platform/modules/presentation/WebPresentationConnectionProxy.h"
+#include "third_party/WebKit/public/platform/modules/presentation/presentation.mojom.h"
+
+namespace content {
+
+// This class connects PrensentationConnection object living in

[mark a. foltz, 2016/10/21 00:53:03]

typo in PresentationConnection

[zhaobin, 2016/10/22 02:44:13]

Done.

+// controller(receiver) render process

[mark a. foltz, 2016/10/21 00:53:03]

... one frame with a PresentationConnection owned by a different frame.

[zhaobin, 2016/10/22 02:44:13]

Done.

+// with PresentationConnection object living in receiver(controller) render
+// process.

[mark a. foltz, 2016/10/21 00:53:03]

It's up to the embedder to decide whether the controller and receiver live in
different processes or not, so it would be more accurate to talk about
connections owned by frames instead of processes.

[zhaobin, 2016/10/22 02:44:13]

Done.

+//
+// |SetSourceConnection| sets |source_connection_| to PresentationConnection
+// object lives in current render process.
+// |SetTargetConnection| sets |target_connection_| to mojo handle of
+// PresentationConnection object lives in remote render process.
+//
+// When both |source_connection_| and |target_connection_| are set,
+// we can send message or notify state changes between controller and receiver.
+//
+// To send message from controller page to receiver page:

[mark a. foltz, 2016/10/21 00:53:03]

controlling frame to receiver frame:

[zhaobin, 2016/10/22 02:44:13]

Done.

+// 1. controller page invokes connection.sendMessage();
+// 2. This call is delegated to controller presentation connection proxy's
+//    SendString().
+//      PresentationConnectionProxy::SendString() {
+//         target_connection_->OnConnectionMessageReceived();
+//      }
+// 3. Receiver PresentationConnectionProxy::OnConnectionMessageReceived() is
+//  invoked.
+// 4. connection.onmessage event on receiver page is fired.
+//
+// Sending message from receiver to controller and notifying state changes
+// between controller and receiver works the same.
+//
+// Instance of this class is only created for 1-UA mode.

[mark a. foltz, 2016/10/21 00:53:03]

s/1-UA mode/offscreen presentations/

[zhaobin, 2016/10/22 02:44:13]

Done.

+class PresentationConnectionProxy
+    : public blink::WebPresentationConnectionProxy,
+      public NON_EXPORTED_BASE(blink::mojom::PresentationConnection) {
+ public:
+  PresentationConnectionProxy();
+  ~PresentationConnectionProxy() override;
+
+  blink::mojom::PresentationConnectionPtr Bind();
+
+  // WebPresentationConnectionProxy Implementation
+  void SetSourceConnection(
+      blink::WebPresentationConnection* connection) override;
+  void SendString(const blink::WebString& message) override;
+  void SendArrayBuffer(const uint8_t* data, size_t length) override;
+
+  // blink::mojom::PresentationConnection implementation
+  void SetTargetConnection(
+      blink::mojom::PresentationConnectionPtr connection) override;
+  void OnConnectionMessageReceived(
+      blink::mojom::SessionMessagePtr message) override;
+
+ private:
+  mojo::Binding<blink::mojom::PresentationConnection> binding_;
+  blink::mojom::PresentationConnectionPtr target_connection_;
+  blink::WebPresentationConnection* source_connection_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_PRESENTATION_PRESENTATION_CONNECTION_PROXY_H_