Minor cleanup of wakelocks, extension ID backup

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadService.kt

@@ -16,9 +16,9 @@ import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.notification.Notifications
 import eu.kanade.tachiyomi.data.preference.PreferencesHelper
 import eu.kanade.tachiyomi.util.lang.plusAssign
+import eu.kanade.tachiyomi.util.system.acquireWakeLock
 import eu.kanade.tachiyomi.util.system.connectivityManager
 import eu.kanade.tachiyomi.util.system.notification
-import eu.kanade.tachiyomi.util.system.powerManager
 import eu.kanade.tachiyomi.util.system.toast
 import rx.android.schedulers.AndroidSchedulers
 import rx.schedulers.Schedulers
@@ -70,9 +70,7 @@ class DownloadService : Service() {
     /**
      * Wake lock to prevent the device to enter sleep mode.
      */
-    private val wakeLock by lazy {
-        powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "DownloadService:WakeLock")
-    }
+    private lateinit var wakeLock: PowerManager.WakeLock
 
     /**
      * Subscriptions to store while the service is running.
@@ -85,6 +83,7 @@ class DownloadService : Service() {
     override fun onCreate() {
         super.onCreate()
         startForeground(Notifications.ID_DOWNLOAD_CHAPTER, getPlaceholderNotification())
+        wakeLock = acquireWakeLock(javaClass.name)
         runningRelay.call(true)
         subscriptions = CompositeSubscription()
         listenDownloaderState()