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

device/usb/usb_device_impl.h

Index: device/usb/usb_device_impl.h
diff --git a/device/usb/usb_device_impl.h b/device/usb/usb_device_impl.h
index 897b4910fe045d33e37bdf4c3df97057ebc9d7a1..a865ea216102645216f3f1c43fe0c5899e636123 100644
--- a/device/usb/usb_device_impl.h
+++ b/device/usb/usb_device_impl.h
@@ -15,9 +15,10 @@
 
 struct libusb_device;
 struct libusb_config_descriptor;
+struct libusb_device_handle;
 
 namespace base {
-class SingleThreadTaskRunner;
+class SequencedTaskRunner;
 }
 
 namespace device {
@@ -25,8 +26,9 @@ namespace device {
 class UsbDeviceHandleImpl;
 class UsbContext;
 
-typedef libusb_device* PlatformUsbDevice;
-typedef libusb_config_descriptor* PlatformUsbConfigDescriptor;
+typedef struct libusb_device* PlatformUsbDevice;
+typedef struct libusb_config_descriptor* PlatformUsbConfigDescriptor;
+typedef struct libusb_device_handle* PlatformUsbDeviceHandle;
 
 class UsbDeviceImpl : public UsbDevice {
  public:
@@ -37,12 +39,9 @@ class UsbDeviceImpl : public UsbDevice {
   void RequestUsbAccess(int interface_id,
                         const ResultCallback& callback) override;
 #endif  // OS_CHROMEOS
-  scoped_refptr<UsbDeviceHandle> Open() override;
+  void Open(const OpenCallback& callback) override;
   bool Close(scoped_refptr<UsbDeviceHandle> handle) override;
   const UsbConfigDescriptor* GetConfiguration() override;
-  bool GetManufacturer(base::string16* manufacturer) override;
-  bool GetProduct(base::string16* product) override;
-  bool GetSerialNumber(base::string16* serial_number) override;
 
  protected:
   friend class UsbServiceImpl;
@@ -50,37 +49,35 @@ class UsbDeviceImpl : public UsbDevice {
 
   // Called by UsbServiceImpl only;
   UsbDeviceImpl(scoped_refptr<UsbContext> context,
-                scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
                 PlatformUsbDevice platform_device,
                 uint16 vendor_id,
                 uint16 product_id,
-                uint32 unique_id);
+                uint32 unique_id,
+                const base::string16& manufacturer_string,
+                const base::string16& product_string,
+                const base::string16& serial_number,
+                scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
 
   ~UsbDeviceImpl() override;
 
   // Called only by UsbServiceImpl.
+  PlatformUsbDevice platform_device() const { return platform_device_; }
+  void set_visited(bool visited) { visited_ = visited; }
+  bool was_visited() const { return visited_; }
   void OnDisconnect();
 
   // Called by UsbDeviceHandleImpl.
   void RefreshConfiguration();
 
  private:
+  void OpenOnBlockingThread(const OpenCallback& callback);
+  void Opened(PlatformUsbDeviceHandle platform_handle,
+              const OpenCallback& callback);
+
   base::ThreadChecker thread_checker_;
   PlatformUsbDevice platform_device_;
+  bool visited_ = false;
 
-  // On Linux these properties are read from sysfs when the device is enumerated
-  // to avoid hitting the permission broker on Chrome OS for a real string
-  // descriptor request.
-  base::string16 manufacturer_;
-  base::string16 product_;
-  base::string16 serial_number_;
-#if !defined(USE_UDEV)
-  // On other platforms the device must be opened in order to cache them. This
-  // should be delayed until the strings are needed to avoid poor interactions
-  // with other applications.
-  void CacheStrings();
-  bool strings_cached_;
-#endif
 #if defined(OS_CHROMEOS)
   // On Chrome OS save the devnode string for requesting path access from
   // permission broker.
@@ -98,8 +95,8 @@ class UsbDeviceImpl : public UsbDevice {
   typedef std::vector<scoped_refptr<UsbDeviceHandleImpl> > HandlesVector;
   HandlesVector handles_;
 
-  // Reference to the UI thread for permission-broker calls.
-  scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbDeviceImpl);
 };