Reland: Introduce the devices Mojo app

device/devices_app/devices_app.cc

+// 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.
+
+#include "device/devices_app/devices_app.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/sequenced_task_runner.h"
+#include "base/thread_task_runner_handle.h"
+#include "base/threading/thread.h"
+#include "base/time/time.h"
+#include "device/core/device_client.h"
+#include "device/devices_app/usb/device_manager_impl.h"
+#include "device/devices_app/usb/public/cpp/device_manager_delegate.h"
+#include "device/usb/usb_service.h"
+#include "mojo/application/public/cpp/application_connection.h"
+#include "mojo/application/public/cpp/application_impl.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/interface_request.h"
+#include "url/gurl.h"
+
+namespace device {
+
+const char kDevicesMojoAppUrl[] = "system:devices";
+
+namespace {
+
+// The number of seconds to wait without any bound DeviceManagers before
+// exiting the app.
+const int64 kIdleTimeoutInSeconds = 10;
+
+// A usb::DeviceManagerDelegate implementation which provides origin-based
+// device access control.
+class USBDeviceManagerDelegate : public usb::DeviceManagerDelegate {
+ public:
+  explicit USBDeviceManagerDelegate(const GURL& remote_url)
+      : remote_url_(remote_url) {}
+  ~USBDeviceManagerDelegate() override {}
+
+ private:
+  // usb::DeviceManagerDelegate:
+  bool IsDeviceAllowed(const usb::DeviceInfo& device) override {
+    // Limited set of conditions to allow localhost connection for testing. This
+    // does not presume to catch all common local host strings.
+    if (remote_url_.host() == "127.0.0.1" || remote_url_.host() == "localhost")
+      return true;
+
+    // Also let browser apps and mojo apptests talk to all devices.
+    if (remote_url_.SchemeIs("system") ||
+        remote_url_ == GURL("mojo://devices_apptests/"))
+      return true;
+
+    // TODO(rockot/reillyg): Implement origin-based device access control.
+    return false;
+  }
+
+  GURL remote_url_;
+
+  DISALLOW_COPY_AND_ASSIGN(USBDeviceManagerDelegate);
+};
+
+// A DeviceClient implementation to be constructed iff the app is not running
+// in an embedder that provides a DeviceClient (i.e. running as a standalone
+// Mojo app, not in Chrome).
+class AppDeviceClient : public DeviceClient {
+ public:
+  explicit AppDeviceClient(
+      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner)
+      : usb_service_(UsbService::GetInstance(blocking_task_runner)) {}
+  ~AppDeviceClient() override {}
+
+ private:
+  // DeviceClient:
+  UsbService* GetUsbService() override { return usb_service_; }
+
+  UsbService* usb_service_;
+};
+
+}  // namespace
+
+// This class insures that a UsbService has been initialized and is accessible
+// via the DeviceClient interface.
+class DevicesApp::USBServiceInitializer {
+ public:
+  USBServiceInitializer()
+      : blocking_thread_("USB service blocking I/O thread") {
+    blocking_thread_.Start();
+    app_device_client_.reset(
+        new AppDeviceClient(blocking_thread_.task_runner()));
+  }
+
+  ~USBServiceInitializer() {}
+
+ private:
+  scoped_ptr<AppDeviceClient> app_device_client_;
+  base::Thread blocking_thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(USBServiceInitializer);
+};
+
+DevicesApp::~DevicesApp() {
+}
+
+// static
+scoped_ptr<mojo::ApplicationDelegate> DevicesApp::CreateDelegate(
+    scoped_refptr<base::SequencedTaskRunner> service_task_runner) {
+  return scoped_ptr<mojo::ApplicationDelegate>(
+      new DevicesApp(service_task_runner));
+}
+
+DevicesApp::DevicesApp(
+    scoped_refptr<base::SequencedTaskRunner> service_task_runner)
+    : app_impl_(nullptr),
+      service_task_runner_(service_task_runner),
+      active_device_manager_count_(0) {
+}
+
+void DevicesApp::Initialize(mojo::ApplicationImpl* app) {
+  app_impl_ = app;
+  if (!service_task_runner_) {
+    service_initializer_.reset(new USBServiceInitializer);
+    service_task_runner_ = base::ThreadTaskRunnerHandle::Get();
+  }
+  StartIdleTimer();
+}
+
+bool DevicesApp::ConfigureIncomingConnection(
+    mojo::ApplicationConnection* connection) {
+  connection->AddService<usb::DeviceManager>(this);
+  return true;
+}
+
+void DevicesApp::Quit() {
+  service_initializer_.reset();
+  app_impl_ = nullptr;
+}
+
+void DevicesApp::Create(mojo::ApplicationConnection* connection,
+                        mojo::InterfaceRequest<usb::DeviceManager> request) {
+  scoped_ptr<usb::DeviceManagerDelegate> delegate(new USBDeviceManagerDelegate(
+      GURL(connection->GetRemoteApplicationURL())));
+
+  // Owned by its message pipe.
+  usb::DeviceManagerImpl* device_manager = new usb::DeviceManagerImpl(
+      request.Pass(), delegate.Pass(), service_task_runner_);
+  device_manager->set_error_handler(this);
+
+  active_device_manager_count_++;
+  idle_timeout_callback_.Cancel();
+}
+
+void DevicesApp::OnConnectionError() {
+  DCHECK_GE(active_device_manager_count_, 0u);
+  active_device_manager_count_--;
+  if (active_device_manager_count_ == 0) {
+    // If the last DeviceManager connection has been dropped, kick off an idle
+    // timeout to shut ourselves down.
+    StartIdleTimer();
+  }
+}
+
+void DevicesApp::StartIdleTimer() {
+  // Passing unretained |app_impl_| is safe here because |app_impl_| is
+  // guaranteed to outlive |this|, and the callback is canceled if |this| is
+  // destroyed.
+  idle_timeout_callback_.Reset(base::Bind(&mojo::ApplicationImpl::Terminate,
+                                          base::Unretained(app_impl_)));
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+      FROM_HERE, idle_timeout_callback_.callback(),
+      base::TimeDelta::FromSeconds(kIdleTimeoutInSeconds));
+}
+
+}  // namespace device