Use the task scheduler for blocking tasks in the USB service on Linux

device/usb/usb_device_android.h

 // 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_USB_USB_DEVICE_ANDROID_H_
 #define DEVICE_USB_USB_DEVICE_ANDROID_H_
 
 #include "base/android/scoped_java_ref.h"
 #include "base/memory/weak_ptr.h"
 #include "device/usb/usb_device.h"
 
-namespace base {
-class SequencedTaskRunner;
-}
-
 namespace device {
 
 class UsbServiceAndroid;
 
 class UsbDeviceAndroid : public UsbDevice {
  public:
   static scoped_refptr<UsbDeviceAndroid> Create(
       JNIEnv* env,
       base::WeakPtr<UsbServiceAndroid> service,
-      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner,
       const base::android::JavaRef<jobject>& usb_device);
 
   // UsbDevice:
   void RequestPermission(const ResultCallback& callback) override;
   bool permission_granted() const override;
   void Open(const OpenCallback& callback) override;
 
   jint device_id() const { return device_id_; }
   void PermissionGranted(bool granted);
 
  private:
   UsbDeviceAndroid(
       JNIEnv* env,
       base::WeakPtr<UsbServiceAndroid> service,
       uint16_t usb_version,
       uint8_t device_class,
       uint8_t device_subclass,
       uint8_t device_protocol,
       uint16_t vendor_id,
       uint16_t product_id,
       uint16_t device_version,
       const base::string16& manufacturer_string,
       const base::string16& product_string,
       const base::string16& serial_number,
-      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner,
       const base::android::JavaRef<jobject>& wrapper);
   ~UsbDeviceAndroid() override;
 
   void CallRequestPermissionCallbacks(bool granted);
   void OnDeviceOpenedToReadDescriptors(
       scoped_refptr<UsbDeviceHandle> device_handle);
   void OnReadDescriptors(scoped_refptr<UsbDeviceHandle> device_handle,
                          std::unique_ptr<UsbDeviceDescriptor> descriptor);
   void OnReadWebUsbDescriptors(
       scoped_refptr<UsbDeviceHandle> device_handle,
       std::unique_ptr<WebUsbAllowedOrigins> allowed_origins,
       const GURL& landing_page);
 
-  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
-
   const jint device_id_;
   bool permission_granted_ = false;
   std::list<ResultCallback> request_permission_callbacks_;
   base::WeakPtr<UsbServiceAndroid> service_;
 
   // Java object org.chromium.device.usb.ChromeUsbDevice.
   base::android::ScopedJavaGlobalRef<jobject> j_object_;
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_DEVICE_ANDROID_H_