Add convenience method for processMessage with no arguments

Similar to StateMachine, this CL adds a convenience method for
processMessage that sets arg1 and arg2 to 0, and obj to null.

Test: SyncStateMachineTest
Change-Id: I7f5b9c0403c1abf02d03fd26bb2a16c53712c3bb
diff --git a/staticlibs/device/com/android/net/module/util/SyncStateMachine.java b/staticlibs/device/com/android/net/module/util/SyncStateMachine.java
index cc113a4..da184d3 100644
--- a/staticlibs/device/com/android/net/module/util/SyncStateMachine.java
+++ b/staticlibs/device/com/android/net/module/util/SyncStateMachine.java
@@ -165,6 +165,11 @@
      * The message is processed sequentially, so calling this method recursively is not permitted.
      * In other words, using this method inside State#enter, State#exit, or State#processMessage
      * is incorrect and will result in an IllegalStateException.
+     *
+     * @param what is assigned to Message.what
+     * @param arg1 is assigned to Message.arg1
+     * @param arg2 is assigned to Message.arg2
+     * @param obj  is assigned to Message.obj
      */
     public final void processMessage(int what, int arg1, int arg2, @Nullable Object obj) {
         ensureCorrectThread();
@@ -189,6 +194,15 @@
         mCurrentlyProcessing = Integer.MIN_VALUE;
     }
 
+    /**
+     * Synchronously process a message and perform state transition.
+     *
+     * @param what is assigned to Message.what.
+     */
+    public final void processMessage(int what) {
+        processMessage(what, 0, 0, null);
+    }
+
     private void maybeProcessSelfMessageQueue() {
         while (!mSelfMsgQueue.isEmpty()) {
             currentStateProcessMessageThenPerformTransitions(mSelfMsgQueue.poll());