Make FdEventsReader#isRunning method as protected.

This allows subclasses of FdEventsReader can access isRunning() method
directly without maintaining its own mechanism to check if the instance
of FdEventsReader is still running.

Bug: 232680956
Bug: 233191218
Test: m
Change-Id: Iaaa07328f9804580cc2e413b5a50c0d69d8cfb2f
diff --git a/staticlibs/device/com/android/net/module/util/FdEventsReader.java b/staticlibs/device/com/android/net/module/util/FdEventsReader.java
index 71ae13d..ecf8e77 100644
--- a/staticlibs/device/com/android/net/module/util/FdEventsReader.java
+++ b/staticlibs/device/com/android/net/module/util/FdEventsReader.java
@@ -211,7 +211,7 @@
         return true;
     }
 
-    private boolean isRunning() {
+    protected boolean isRunning() {
         return (mFd != null) && mFd.valid();
     }