arc-bridge: Add the ARC Bridge Service

components/arc/arc_bridge_service.h

Index: components/arc/arc_bridge_service.h
diff --git a/components/arc/arc_bridge_service.h b/components/arc/arc_bridge_service.h
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+// 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 COMPONENTS_ARC_ARC_BRIDGE_SERVICE_H_
+#define COMPONENTS_ARC_ARC_BRIDGE_SERVICE_H_
+
+#include "base/macros.h"
+#include "base/observer_list.h"
+#include "base/sequenced_task_runner.h"
+#include "ipc/ipc_channel_proxy.h"
+#include "ipc/ipc_listener.h"
+#include "ipc/ipc_message.h"
+
+namespace arc {
+
+// The Chrome-side service that handles ARC instances and ARC bridge creation.
+// This service handles the lifetime of ARC instances and sets up the
+// communication channel (the ARC bridge) used to send and receive messages.
+class ArcBridgeService : public IPC::Listener {
+ public:
+  // The possible states of the bridge.  In the normal flow, the state changes
+  // in the following sequence:
+  //
+  // STOPPED
+  //   SetAvailable(true) + HandleStartup() -> SocketConnect() ->
+  // CONNECTING
+  //   Connect() ->
+  // CONNECTED
+  //   SocketConnectAfterSetSocketPermissions() ->
+  // STARTING
+  //   StartInstance() -> OnInstanceReady() ->
+  // READY
+  //
+  // When Shutdown() is called, the state changes depending on the state it was
+  // at:
+  //
+  // CONNECTED/CONNECTING -> STOPPED
+  // STARTING/READY -> STOPPING -> StopInstance() -> STOPPED
+  enum class State {
+    // ARC is not currently running.
+    STOPPED,
+
+    // The request to connect has been sent.
+    CONNECTING,
+
+    // The bridge has connected to the socket, but has not started the ARC
+    // instance.
+    CONNECTED,
+
+    // The ARC bridge has been set up and ARC is starting up.
+    STARTING,
+
+    // The ARC instance has been fully initialized and is now ready for user
+    // interaction.
+    READY,
+
+    // The ARC instance has started shutting down.
+    STOPPING,
+  };
+
+  class Observer {
+   public:
+    // Called whenever the state of the bridge has changed.
+    virtual void OnStateChanged(State state) {}
+
+    // Called whenever ARC's availability has changed for this system.
+    virtual void OnAvailableChanged(bool available) {}
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  ArcBridgeService(
+      const scoped_refptr<base::SingleThreadTaskRunner>& ipc_task_runner,
+      const scoped_refptr<base::SequencedTaskRunner>& file_task_runner);
+  ~ArcBridgeService() override;
+
+  // Gets the global instance of the ARC Bridge Service. This can only be
+  // called on the thread that this class was created on.
+  static ArcBridgeService* Get();
+
+  // DetectAvailability() should be called once D-Bus is available. It will
+  // call CheckArcAvailability() on the session_manager. This can only be
+  // called on the thread that this class was created on.
+  void DetectAvailability();
+
+  // HandleStartup() should be called upon profile startup.  This will only
+  // launch an instance if the instance service is available and it is enabled.
+  // This can only be called on the thread that this class was created on.
+  void HandleStartup();
+
+  // Shutdown() should be called when the browser is shutting down. This can
+  // only be called on the thread that this class was created on.
+  void Shutdown();
+
+  // Adds or removes observers. This can only be called on the thread that this
+  // class was created on.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  // Gets the current state of the bridge service.
+  State state() const { return state_; }
+
+  // Gets if ARC is available in this system.
+  bool available() const { return available_; }
+
+  // Requests registration of an input device on the ARC instance.
+  // TODO(denniskempin): Make this interface more typesafe.
+  // |name| should be the displayable name of the emulated device (e.g. "Chrome
+  // OS Keyboard"), |device_type| the name of the device type (e.g. "keyboard")
+  // and |fd| a file descriptor that emulates the kernel events of the device.
+  // This can only be called on the thread that this class was created on.
+  bool RegisterInputDevice(const std::string& name,
+                           const std::string& device_type,
+                           base::ScopedFD fd);
+
+ private:
+  friend class ArcBridgeTest;
+  FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, Basic);
+  FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, ShutdownMidStartup);
+
+  // If all pre-requisites are true (ARC is available, it has been enabled, and
+  // the session has started), and ARC is stopped, start ARC. If ARC is running
+  // and the pre-requisites stop being true, stop ARC.
+  void PrerequisitesChanged();
+
+  // Binds to the socket specified by |socket_path|.
+  void SocketConnect(const base::FilePath& socket_path);
+
+  // Binds to the socket specified by |socket_path| after creating its parent
+  // directory is present.
+  void SocketConnectAfterEnsureParentDirectory(
+      const base::FilePath& socket_path,
+      bool directory_present);
+
+  // Internal connection method. Separated to make testing easier.
+  bool Connect(const IPC::ChannelHandle& handle, IPC::Channel::Mode mode);
+
+  // Finishes connecting after setting socket permissions.
+  void SocketConnectAfterSetSocketPermissions(const base::FilePath& socket_path,
+                                              bool socket_permissions_success);
+
+  // Stops the running instance.
+  void StopInstance();
+
+  // Called when the ARC instance has finished setting up and is ready for user
+  // interaction.
+  void OnInstanceReady();
+
+  // Changes the current state and notifies all observers.
+  void SetState(State state);
+
+  // IPC::Listener:
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+  // DBus callbacks.
+  void OnArcAvailable(bool available);
+  void OnInstanceStarted(bool success);
+  void OnInstanceStopped(bool success);
+
+  scoped_refptr<base::SequencedTaskRunner> origin_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> ipc_task_runner_;
+  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
+
+  scoped_ptr<IPC::ChannelProxy> ipc_channel_;
+
+  base::ObserverList<Observer> observer_list_;
+
+  // If the user's session has started.
+  bool session_started_;
+
+  // If the ARC instance service is available.
+  bool available_;
+
+  // The current state of the bridge.
+  ArcBridgeService::State state_;
+
+  // WeakPtrFactory to use callbacks.
+  base::WeakPtrFactory<ArcBridgeService> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcBridgeService);
+};
+
+}  // namespace arc
+
+#endif  // COMPONENTS_ARC_ARC_BRIDGE_SERVICE_H_