Move device/usb classes from the FILE thread to UI thread.

device/usb/usb_service_impl.h

Index: device/usb/usb_service_impl.h
diff --git a/device/usb/usb_service_impl.h b/device/usb/usb_service_impl.h
index 44fff41084c71235a583484befb306e9e285ef3e..e4c44438aab95a2c5badde26415cd45ff6353599 100644
--- a/device/usb/usb_service_impl.h
+++ b/device/usb/usb_service_impl.h
@@ -5,42 +5,92 @@
 #include "device/usb/usb_service.h"
 
 #include <map>
+#include <set>
 
 #include "base/memory/weak_ptr.h"
-#include "base/single_thread_task_runner.h"
+#include "base/message_loop/message_loop.h"
 #include "device/usb/usb_context.h"
 #include "device/usb/usb_device_impl.h"
 #include "third_party/libusb/src/libusb/libusb.h"
 
+#if defined(OS_WIN)
+#include "base/scoped_observer.h"
+#include "device/core/device_monitor_win.h"
+#endif  // OS_WIN
+
+struct libusb_device;
+struct libusb_context;
+
+namespace base {
+class SequencedTaskRunner;
+class SingleThreadTaskRunner;
+}
+
 namespace device {
 
 typedef struct libusb_device* PlatformUsbDevice;
 typedef struct libusb_context* PlatformUsbContext;
 
-class UsbServiceImpl : public UsbService {
+class UsbServiceImpl : public UsbService,
+#if defined(OS_WIN)
+                       public DeviceMonitorWin::Observer,
+#endif  // OS_WIN
+                       public base::MessageLoop::DestructionObserver {
  public:
   static UsbService* Create(
-      scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);
+      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
 
  private:
   explicit UsbServiceImpl(
       PlatformUsbContext context,
-      scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);
+      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
   ~UsbServiceImpl() override;
 
   // device::UsbService implementation
   scoped_refptr<UsbDevice> GetDeviceById(uint32 unique_id) override;
-  void GetDevices(std::vector<scoped_refptr<UsbDevice>>* devices) override;
-
-  // Enumerate USB devices from OS and update devices_ map.
-  void RefreshDevices();
+  void GetDevices(const GetDevicesCallback& callback) override;
 
 #if defined(OS_WIN)
-  void RefreshDevicesIfWinUsbDevice(const std::string& device_path);
+  // device::DeviceMonitorWin::Observer implementation
+  void OnDeviceAdded(const GUID& class_guid,
+                     const std::string& device_path) override;
+  void OnDeviceRemoved(const GUID& class_guid,
+                       const std::string& device_path) override;
 #endif  // OS_WIN
 
+  // base::MessageLoop::DestructionObserver implementation
+  void WillDestroyCurrentMessageLoop() override;
+
+  // Enumerate USB devices from OS and update devices_ map. |new_device_path| is
+  // an optional hint used on Windows to prevent enumerations before drivers for
+  // a new device have been completely loaded.
+  void RefreshDevices(const std::string& new_device_path);
+
+  static void RefreshDevicesOnBlockingThread(
+      base::WeakPtr<UsbServiceImpl> usb_service,
+      const std::string& new_device_path,
+      scoped_refptr<base::SequencedTaskRunner> task_runner,
+      scoped_refptr<UsbContext> usb_context,
+      const std::set<PlatformUsbDevice>& previous_devices);
+
+  static void AddDeviceOnBlockingThread(
+      base::WeakPtr<UsbServiceImpl> usb_service,
+      scoped_refptr<base::SequencedTaskRunner> task_runner,
+      PlatformUsbDevice platform_device);
+
+  void RefreshDevicesComplete(libusb_device** platform_devices,
+                              ssize_t device_count);
+
   // Adds a new UsbDevice to the devices_ map based on the given libusb device.
-  scoped_refptr<UsbDeviceImpl> AddDevice(PlatformUsbDevice platform_device);
+  void AddDevice(PlatformUsbDevice platform_device,
+                 uint16 vendor_id,
+                 uint16 product_id,
+                 base::string16 manufacturer_string,
+                 base::string16 product_string,
+                 base::string16 serial_number,
+                 std::string device_node);
+
+  void RemoveDevice(scoped_refptr<UsbDeviceImpl> device);
 
   // Handle hotplug events from libusb.
   static int LIBUSB_CALL HotplugCallback(libusb_context* context,
@@ -48,27 +98,26 @@ class UsbServiceImpl : public UsbService {
                                          libusb_hotplug_event event,
                                          void* user_data);
   // These functions release a reference to the provided platform device.
-  void OnDeviceAdded(PlatformUsbDevice platform_device);
-  void OnDeviceRemoved(PlatformUsbDevice platform_device);
+  void OnPlatformDeviceAdded(PlatformUsbDevice platform_device);
+  void OnPlatformDeviceRemoved(PlatformUsbDevice platform_device);
 
   scoped_refptr<UsbContext> context_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
-
-#if defined(OS_WIN)
-  class UIThreadHelper;
-  UIThreadHelper* ui_thread_helper_;
-#endif  // OS_WIN
+  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   // TODO(reillyg): Figure out a better solution for device IDs.
-  uint32 next_unique_id_;
+  uint32 next_unique_id_ = 0;
 
   // When available the device list will be updated when new devices are
   // connected instead of only when a full enumeration is requested.
   // TODO(reillyg): Support this on all platforms. crbug.com/411715
-  bool hotplug_enabled_;
+  bool hotplug_enabled_ = false;
   libusb_hotplug_callback_handle hotplug_handle_;
 
+  // Enumeration callbacks are queued until an enumeration completes.
+  bool enumeration_ready_ = false;
+  std::vector<GetDevicesCallback> pending_enumerations_;
+
   // The map from unique IDs to UsbDevices.
   typedef std::map<uint32, scoped_refptr<UsbDeviceImpl>> DeviceMap;
   DeviceMap devices_;
@@ -78,6 +127,10 @@ class UsbServiceImpl : public UsbService {
       PlatformDeviceMap;
   PlatformDeviceMap platform_devices_;
 
+#if defined(OS_WIN)
+  ScopedObserver<DeviceMonitorWin, DeviceMonitorWin::Observer> device_observer_;
+#endif  // OS_WIN
+
   base::WeakPtrFactory<UsbServiceImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbServiceImpl);