Reland: Introduce the devices Mojo app

device/devices_app/devices_app.h

Index: device/devices_app/devices_app.h
diff --git a/device/devices_app/devices_app.h b/device/devices_app/devices_app.h
new file mode 100644
index 0000000000000000000000000000000000000000..4b04568534b7ebdc91b62ed1f7d3373787be34bc
--- /dev/null
+++ b/device/devices_app/devices_app.h
@@ -0,0 +1,81 @@
+// 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 DEVICE_DEVICES_DEVICES_APP_H_
+#define DEVICE_DEVICES_DEVICES_APP_H_
+
+#include "base/cancelable_callback.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "mojo/application/public/cpp/application_delegate.h"
+#include "mojo/application/public/cpp/interface_factory.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h"
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace mojo {
+class ApplicationImpl;
+}
+
+namespace device {
+
+namespace usb {
+class DeviceManager;
+}
+
+extern const char kDevicesMojoAppUrl[];
+
+class DevicesApp : public mojo::ApplicationDelegate,
+                   public mojo::InterfaceFactory<usb::DeviceManager>,
+                   public mojo::ErrorHandler {
+ public:
+  ~DevicesApp() override;
+
+  // |service_task_runner| is the thread TaskRunner on which the UsbService
+  // lives. This argument should be removed once UsbService is owned by the
+  // USB device manager and no longer part of the public device API. If null,
+  // the app will construct its own DeviceClient and UsbService.
+  static scoped_ptr<mojo::ApplicationDelegate> CreateDelegate(
+      scoped_refptr<base::SequencedTaskRunner> service_task_runner);
+
+ private:
+  class USBServiceInitializer;
+
+  DevicesApp(scoped_refptr<base::SequencedTaskRunner> service_task_runner);
+
+  // mojo::ApplicationDelegate:
+  void Initialize(mojo::ApplicationImpl* app) override;
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override;
+  void Quit() override;
+
+  // mojo::InterfaceFactory<usb::DeviceManager>:
+  void Create(mojo::ApplicationConnection* connection,
+              mojo::InterfaceRequest<usb::DeviceManager> request) override;
+
+  // mojo::ErrorHandler:
+  void OnConnectionError() override;
+
+  // Sets the app for destruction after a period of idle time. If any top-level
+  // services (e.g. usb::DeviceManager) are bound before the timeout elapses,
+  // it's canceled.
+  void StartIdleTimer();
+
+  mojo::ApplicationImpl* app_impl_;
+  scoped_ptr<USBServiceInitializer> service_initializer_;
+  scoped_refptr<base::SequencedTaskRunner> service_task_runner_;
+  size_t active_device_manager_count_;
+
+  // Callback used to shut down the app after a period of inactivity.
+  base::CancelableClosure idle_timeout_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(DevicesApp);
+};
+
+}  // naespace device
+
+#endif  // DEVICE_DEVICES_DEVICES_APP_H_