Implement BroadcastChannel

third_party/WebKit/Source/modules/broadcastchannel/BroadcastChannelConnection.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 BroadcastChannelConnection_h
+#define BroadcastChannelConnection_h
+
+#include "components/webmessaging/public/interfaces/broadcast_channel.mojom-blink.h"
+#include "mojo/public/cpp/bindings/associated_binding.h"
+#include "platform/weborigin/SecurityOriginHash.h"
+#include "wtf/ListHashSet.h"
+#include "wtf/text/StringHash.h"
+
+namespace blink {
+
+// To ensure proper message ordering, all BroadcastChannel instances on the same
+// thread share a single mojo connection. This class represents such a
+// connection. BroadcastChannel instances register themselves with the correct
+// connection, and use the connection to broadcast messages.
+class BroadcastChannelConnection final : public webmessaging::mojom::blink::BroadcastChannelClient {
+    WTF_MAKE_NONCOPYABLE(BroadcastChannelConnection);
+public:
+    class Client {
+    public:
+        virtual String name() const = 0;
+        virtual SecurityOrigin* origin() const = 0;
+
+        // Called when a message is received for this channel. Not called for
+        // messages send by this client to the channel.
+        virtual void onMessage(const String& message) = 0;
+
+        // Called when the connection this client is registered with closes.
+        // After onError is called a client should not try to do anything with
+        // the connection anymore.
+        virtual void onError() = 0;
+    };
+
+    // Returns the BroadcastChannelConnection instance to use for the channel
+    // identified by the particular origin and name. When called with the same
+    // parameters on the same thread this will always return the same instance,
+    // except if for some reason the mojo connection got severed.
+    // If all clients using this particular connection get closed, the
+    // connection itself might also be closed, in which case the next time the
+    // method is called a new connection is created.
+    static BroadcastChannelConnection* getForChannel(const RefPtr<SecurityOrigin>&, const String& name);
+    ~BroadcastChannelConnection();
+
+    // Register a new client that uses this connection. The client must call
+    // unregisterClient when the client object is destroyed.
+    void registerClient(Client*);
+    void unregisterClient(Client*);
+
+    // Broadcasts a message to the channel this connection is for. The message
+    // will be delivered to all clients except the client that send the message.
+    void broadcast(Client*, const String& message);
+private:
+    BroadcastChannelConnection(const String& name, const RefPtr<SecurityOrigin>&, webmessaging::mojom::blink::BroadcastChannelClientAssociatedPtrInfo*, mojo::AssociatedGroup*);
+
+    // webmessaging::mojom::blink::BroadcastChannelClient:
+    void OnMessage(const String& message) override;
+
+    // Called when the mojo binding disconnects. Destroys this connection
+    // object.
+    void onError();
+
+    String m_name;
+    RefPtr<SecurityOrigin> m_origin;
+    ListHashSet<Client*> m_clients;
+    mojo::AssociatedBinding<webmessaging::mojom::blink::BroadcastChannelClient> m_binding;
+};
+
+} // namespace blink
+
+#endif // BroadcastChannelConnection_h