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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+++ 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_threadsafe.h"
+#include "base/sequenced_task_runner.h"
+#include "chromeos/dbus/dbus_method_call_status.h"
+#include "ipc/ipc_channel_proxy.h"
+#include "ipc/ipc_listener.h"
+#include "ipc/ipc_message.h"
+
+class PrefRegistrySimple;
+class PrefService;
+
+namespace arc {
+
+class ArcBridgeTest;
+
+// 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
+  //   SetEnabled(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 State {

[dcheng, 2015/11/06 01:35:28]

Consider using an enum class.

[lhc(google), 2015/11/06 04:14:16]

Done.

+    // 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 enabled status has changed for this session.
+    virtual void OnEnabledChanged(bool enabled) {}
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  explicit ArcBridgeService(
+      const scoped_refptr<base::SequencedTaskRunner>& file_task_runner);
+  virtual ~ArcBridgeService();
+
+  // 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();
+
+  // Shuts down the running instance, if any.  This is safe to call even if
+  // there is no instance running.
+  void Shutdown();
+
+  // Adds or removes observers.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  // Gets the current state of the bridge service.
+  State GetState() const { return state_; }

[dcheng, 2015/11/06 01:35:28]

Nit: google style is to name this state(), since it's a simple inlined accessor.

[lhc(google), 2015/11/06 04:14:17]

Done.

+
+  // Enables or disables the bridge for this session.
+  void SetEnabled(bool enabled);
+
+  // Gets if the bridge is enabled for this session.
+  bool IsEnabled() const { return enabled_; }

[dcheng, 2015/11/06 01:35:28]

Ditto: should just be:
bool enabled() const { return enabled_; }

[lhc(google), 2015/11/06 04:14:16]

Done.

+
+  // 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;
+
+  // 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);
+
+  // Called when the ARC instance has finished setting up and is ready for user
+  // interaction.
+  void OnInstanceReady();
+
+  // Changes the current state and notify all observers.
+  void SetState(State state);
+
+  // IPC::Listener:
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+  // DBus callbacks.
+  void OnInstanceStarted(bool success);
+  void OnInstanceStopped(bool success);
+
+  // Thread in which IPC messaging is performed.
+  base::Thread ipc_thread_;
+
+  // Task runner on which incoming messages are handled.
+  scoped_refptr<base::SequencedTaskRunner> origin_task_runner_;
+
+  // Task runner on which file operations are performed.
+  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
+
+  // The channel through which messages are sent.
+  scoped_ptr<IPC::ChannelProxy> ipc_channel_;
+
+  // A Lock that guards the |ipc_channel_|.  Most of the methods are expected
+  // to be run in the same thread (the one in which the ArcBridgeService
+  // instance was created), but all the ones that send IPC messages can be
+  // called from any method.  This will prevent the |ipc_channel_| from being
+  // destroyed while a message is being sent.
+  base::Lock ipc_channel_lock_;
+
+  // List of observers to notify of state changes.
+  scoped_refptr<base::ObserverListThreadSafe<Observer>> observer_list_;
+
+  // If the ARC instance service is available.
+  bool available_;
+
+  // If ARC has been enabled by policy and user choice.
+  bool enabled_;
+
+  // 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_