Dont block main thread when we try to stop FCM fetch service.

app/src/main/java/org/thoughtcrime/securesms/gcm/FcmFetchForegroundService.kt

@@ -47,6 +47,7 @@ class FcmFetchForegroundService : Service() {
     return if (intent != null && intent.getBooleanExtra(KEY_STOP_SELF, false)) {
       stopForeground(true)
       stopSelf()
+      FcmFetchManager.onForegroundFetchServiceStop()
       START_NOT_STICKY
     } else {
       START_STICKY

app/src/main/java/org/thoughtcrime/securesms/gcm/FcmFetchManager.kt

@@ -39,6 +39,9 @@ object FcmFetchManager {
   @Volatile
   private var startedForeground = false
 
+  @Volatile
+  private var stoppingForeground = false
+
   /**
    * @return True if a service was successfully started, otherwise false.
    */
@@ -89,6 +92,7 @@ object FcmFetchManager {
         if (startedForeground) {
           try {
             context.startService(FcmFetchForegroundService.buildStopIntent(context))
+            stoppingForeground = true
           } catch (e: IllegalStateException) {
             Log.w(TAG, "Failed to stop the foreground notification!", e)
           }
@@ -102,7 +106,10 @@ object FcmFetchManager {
   @JvmStatic
   fun tryLegacyFallback(context: Context) {
     synchronized(this) {
-      if (startedForeground) {
+      if (startedForeground || stoppingForeground) {
+        if (stoppingForeground) {
+          Log.i(TAG, "Legacy fallback: foreground service is stopping, but trying to run in background anyways.")
+        }
         val performedReplace = EXECUTOR.enqueue { fetch(context) }
 
         if (performedReplace) {
@@ -134,4 +141,11 @@ object FcmFetchManager {
       }
     }
   }
+
+  fun onForegroundFetchServiceStop() {
+    synchronized(this) {
+      stoppingForeground = false
+      Log.i(TAG, "Foreground service stopped successfully")
+    }
+  }
 }