[DO NOT MERGE] Guard against launching permission backup/restore twice per request

It looks like there is some case where AbstractRemoteService would #run the
same PendingRequest the second time which violates AsyncTask assumption.

Fixes: 135986503
Test: atest android.permission.cts.PermissionControllerTest
Change-Id: I2d072714ee0fad3c365ff7eb191d690056c0931a

core/java/android/permission/PermissionControllerManager.java

@@ -808,6 +808,9 @@ public final class PermissionControllerManager {
 
         @Override
         public void run() {
+            if (mBackupReader.getStatus() != AsyncTask.Status.PENDING) {
+                return;
+            }
             mBackupReader.execute();
 
             ParcelFileDescriptor remotePipe = mBackupReader.getRemotePipe();
@@ -919,6 +922,9 @@ public final class PermissionControllerManager {
 
         @Override
         public void run(@NonNull IPermissionController service) {
+            if (mBackupSender.getStatus() != AsyncTask.Status.PENDING) {
+                return;
+            }
             mBackupSender.execute(mBackup);
 
             ParcelFileDescriptor remotePipe = mBackupSender.getRemotePipe();