Run all AsyncTasks on thread pool executor

Should Fix #7002

src/org/thoughtcrime/securesms/preferences/AdvancedPreferenceFragment.java

@@ -6,6 +6,7 @@ import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.net.Uri;
+import android.os.AsyncTask;
 import android.os.Bundle;
 import android.provider.ContactsContract;
 import android.support.annotation.NonNull;
@@ -218,7 +219,7 @@ public class AdvancedPreferenceFragment extends CorrectedPreferenceFragment {
         builder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
           @Override
           public void onClick(DialogInterface dialog, int which) {
-            new DisablePushMessagesTask((CheckBoxPreference)preference).execute();
+            new DisablePushMessagesTask((CheckBoxPreference)preference).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
           }
         });
         builder.show();

src/org/thoughtcrime/securesms/preferences/MmsPreferencesFragment.java

@@ -53,7 +53,7 @@ public class MmsPreferencesFragment extends CorrectedPreferenceFragment {
   @Override
   public void onResume() {
     super.onResume();
-    new LoadApnDefaultsTask().execute();
+    new LoadApnDefaultsTask().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
   }
 
   private class LoadApnDefaultsTask extends AsyncTask<Void, Void, LegacyMmsConnection.Apn> {

src/org/thoughtcrime/securesms/preferences/NotificationsPreferenceFragment.java

@@ -106,7 +106,7 @@ public class NotificationsPreferenceFragment extends ListSummaryPreferenceFragme
           MessageNotifier.updateNotification(getActivity(), masterSecret);
           return null;
         }
-      }.execute();
+      }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
 
       return super.onPreferenceChange(preference, value);
     }

src/org/thoughtcrime/securesms/preferences/widgets/ProfilePreference.java

@@ -87,7 +87,7 @@ public class ProfilePreference extends Preference {
       protected void onPostExecute(@NonNull Drawable contactPhoto) {
         avatarView.setImageDrawable(contactPhoto);
       }
-    }.execute();
+    }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
 
     if (!TextUtils.isEmpty(profileName)) {
       profileNameView.setText(profileName);

src/org/thoughtcrime/securesms/preferences/widgets/RingtonePreferenceDialogFragmentCompat.java

@@ -314,7 +314,7 @@ public class RingtonePreferenceDialogFragmentCompat extends PreferenceDialogFrag
             }
           }
         };
-        installTask.execute(fileUri);
+        installTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, fileUri);
       } else {
         ListView listView = ((AlertDialog) getDialog()).getListView();
         listView.setItemChecked(selectedIndex, true);