arc-bridge: Add the ARC Bridge Service

components/arc/arc_bridge_service.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 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 {
+
+class ArcBridgeTest;

[jochen (gone - plz use gerrit), 2015/11/12 23:40:59]

should not be required

[Luis Héctor Chávez, 2015/11/13 00:29:29]

Done.

+
+// 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.

[jochen (gone - plz use gerrit), 2015/11/12 23:40:59]

A better comment would point out that you can only invoke this on the thread
that this class was created on

in general, please add comments to all public methods about the thread they may
be invoked on

[Luis Héctor Chávez, 2015/11/13 00:29:29]

Done.

+  static ArcBridgeService* Get();
+
+  // DetectAvailability() should be called once D-Bus is available. It will
+  // call CheckArcAvailability() on the session_manager.
+  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.
+  void HandleStartup();
+
+  // Shutdown() should be called when the browser is shutting down.
+  void Shutdown();
+
+  // Adds or removes observers.
+  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.
+  bool RegisterInputDevice(const std::string& name,
+                           const std::string& device_type,
+                           base::ScopedFD fd);
+
+ private:
+  friend class arc::ArcBridgeTest;
+  FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, Basic);
+  FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, ShutdownWhenDisabled);
+
+  // 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);
+
+  // Task runner on which incoming messages are handled.
+  scoped_refptr<base::SequencedTaskRunner> origin_task_runner_;
+
+  // Task runner on which ipc operations are performed.
+  scoped_refptr<base::SingleThreadTaskRunner> ipc_task_runner_;
+
+  // Task runner on which file operations are performed.

[jochen (gone - plz use gerrit), 2015/11/12 23:40:59]

i'd encourage you to remove comments that just restate what the code does.

[Luis Héctor Chávez, 2015/11/13 00:29:29]

Done.

+  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
+
+  // The channel through which messages are sent.
+  scoped_ptr<IPC::ChannelProxy> ipc_channel_;
+
+  // List of observers to notify of state changes.
+  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_