Use coroutine job for fetching next source page

(cherry picked from commit e6f3cd03bb)

# Conflicts:
#	app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourcePresenter.kt

app/src/main/java/exh/md/follows/MangaDexFollowsPager.kt

@@ -1,22 +1,14 @@
 package exh.md.follows
 
-import eu.kanade.tachiyomi.source.model.MangasPage
 import eu.kanade.tachiyomi.source.online.all.MangaDex
 import eu.kanade.tachiyomi.ui.browse.source.browse.Pager
-import eu.kanade.tachiyomi.util.lang.runAsObservable
-import rx.Observable
-import rx.android.schedulers.AndroidSchedulers
-import rx.schedulers.Schedulers
 
 /**
  * LatestUpdatesPager inherited from the general Pager.
  */
 class MangaDexFollowsPager(val source: MangaDex) : Pager() {
 
-    override fun requestNext(): Observable<MangasPage> {
-        return runAsObservable({ source.fetchFollows(currentPage) })
-            .subscribeOn(Schedulers.io())
-            .observeOn(AndroidSchedulers.mainThread())
-            .doOnNext { onPageReceived(it) }
+    override suspend fun requestNextPage() {
+        onPageReceived(source.fetchFollows(currentPage))
     }
 }

app/src/main/java/exh/md/similar/MangaDexSimilarPager.kt

@@ -2,30 +2,22 @@ package exh.md.similar
 
 import eu.kanade.tachiyomi.data.database.models.Manga
 import eu.kanade.tachiyomi.data.database.models.toMangaInfo
-import eu.kanade.tachiyomi.source.model.MangasPage
 import eu.kanade.tachiyomi.source.online.all.MangaDex
 import eu.kanade.tachiyomi.ui.browse.source.browse.NoResultsException
 import eu.kanade.tachiyomi.ui.browse.source.browse.Pager
-import eu.kanade.tachiyomi.util.lang.runAsObservable
-import rx.Observable
-import rx.android.schedulers.AndroidSchedulers
-import rx.schedulers.Schedulers
 
 /**
  * MangaDexSimilarPager inherited from the general Pager.
  */
 class MangaDexSimilarPager(val manga: Manga, val source: MangaDex) : Pager() {
 
-    override fun requestNext(): Observable<MangasPage> {
-        return runAsObservable({ source.getMangaSimilar(manga.toMangaInfo()) })
-            .subscribeOn(Schedulers.io())
-            .observeOn(AndroidSchedulers.mainThread())
-            .doOnNext {
-                if (it.mangas.isNotEmpty()) {
-                    onPageReceived(it)
-                } else {
-                    throw NoResultsException()
-                }
-            }
+    override suspend fun requestNextPage() {
+        val mangasPage = source.getMangaSimilar(manga.toMangaInfo())
+
+        if (mangasPage.mangas.isNotEmpty()) {
+            onPageReceived(mangasPage)
+        } else {
+            throw NoResultsException()
+        }
     }
 }