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

device/usb/usb_device_android.cc

Index: device/usb/usb_device_android.cc
diff --git a/device/usb/usb_device_android.cc b/device/usb/usb_device_android.cc
index 7f98ec6f5d02f4092f4b73282247d9ca444bd9d0..692be666e946c39971b342ce1eaa074a168bdf3a 100644
--- a/device/usb/usb_device_android.cc
+++ b/device/usb/usb_device_android.cc
@@ -8,6 +8,7 @@
 #include "base/android/jni_string.h"
 #include "base/bind.h"
 #include "base/location.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "device/usb/usb_configuration_android.h"
 #include "device/usb/usb_descriptors.h"
@@ -23,11 +24,23 @@ using base::android::ScopedJavaLocalRef;
 
 namespace device {
 
+namespace {
+
+scoped_refptr<base::SequencedTaskRunner> CreateBlockingTaskRunner() {
+  return base::CreateSequencedTaskRunnerWithTraits(
+      base::TaskTraits()
+          .MayBlock()
+          .WithPriority(base::TaskPriority::USER_VISIBLE)
+          .WithShutdownBehavior(
+              base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN));
+}
+
+}  // namespace
+
 // static
 scoped_refptr<UsbDeviceAndroid> UsbDeviceAndroid::Create(
     JNIEnv* env,
     base::WeakPtr<UsbServiceAndroid> service,
-    scoped_refptr<base::SequencedTaskRunner> blocking_task_runner,
     const JavaRef<jobject>& usb_device) {
   ScopedJavaLocalRef<jobject> wrapper =
       Java_ChromeUsbDevice_create(env, usb_device);
@@ -51,8 +64,7 @@ scoped_refptr<UsbDeviceAndroid> UsbDeviceAndroid::Create(
       Java_ChromeUsbDevice_getDeviceProtocol(env, wrapper),
       Java_ChromeUsbDevice_getVendorId(env, wrapper),
       Java_ChromeUsbDevice_getProductId(env, wrapper), device_version,
-      manufacturer_string, product_string, serial_number, blocking_task_runner,
-      wrapper));
+      manufacturer_string, product_string, serial_number, wrapper));
 }
 
 void UsbDeviceAndroid::RequestPermission(const ResultCallback& callback) {
@@ -73,7 +85,7 @@ void UsbDeviceAndroid::Open(const OpenCallback& callback) {
         service_->OpenDevice(env, j_object_);
     if (!connection.is_null()) {
       device_handle = UsbDeviceHandleAndroid::Create(
-          env, this, blocking_task_runner_, connection);
+          env, this, CreateBlockingTaskRunner(), connection);
       handles().push_back(device_handle.get());
     }
   }
@@ -98,7 +110,6 @@ UsbDeviceAndroid::UsbDeviceAndroid(
     const base::string16& manufacturer_string,
     const base::string16& product_string,
     const base::string16& serial_number,
-    scoped_refptr<base::SequencedTaskRunner> blocking_task_runner,
     const JavaRef<jobject>& wrapper)
     : UsbDevice(usb_version,
                 device_class,
@@ -110,7 +121,6 @@ UsbDeviceAndroid::UsbDeviceAndroid(
                 manufacturer_string,
                 product_string,
                 serial_number),
-      blocking_task_runner_(blocking_task_runner),
       device_id_(Java_ChromeUsbDevice_getDeviceId(env, wrapper)),
       service_(service),
       j_object_(wrapper) {