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

device/usb/usb_service_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_SERVICE_ANDROID_H_
 #define DEVICE_USB_USB_SERVICE_ANDROID_H_
 
-#include <string>
+#include <jni.h>
+
 #include <unordered_map>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "device/usb/usb_device_android.h"
 #include "device/usb/usb_service.h"
 
-namespace base {
-class SequencedTaskRunner;
-}
+namespace device {
 
-namespace device {
+class UsbDeviceAndroid;
 
 // USB service implementation for Android. This is a stub implementation that
 // does not return any devices.
 class UsbServiceAndroid : public UsbService {
  public:
   // Register C++ methods exposed to Java using JNI.
   static bool RegisterJNI(JNIEnv* env);
 
-  UsbServiceAndroid(
-      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
+  UsbServiceAndroid();
   ~UsbServiceAndroid() override;
 
   // Methods called by Java.
   void DeviceAttached(JNIEnv* env,
                       const base::android::JavaRef<jobject>& caller,
                       const base::android::JavaRef<jobject>& usb_device);
   void DeviceDetached(JNIEnv* env,
                       const base::android::JavaRef<jobject>& caller,
                       jint device_id);
   void DevicePermissionRequestComplete(
@@ skipping 16 matching lines @@
 
   // Java object org.chromium.device.usb.ChromeUsbService.
   base::android::ScopedJavaGlobalRef<jobject> j_object_;
 
   base::WeakPtrFactory<UsbServiceAndroid> weak_factory_;
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_SERVICE_ANDROID_H_