Generate renewal and expiry events

The android timer class was not generating timer events correctly. This caused
renewal and expiration events not to be sent. A strong pointer to the
timer thread was not held and this caused the android util timer
thread to exit after firing once. This is now addressed.

Bug: 8736545

Merge of https://widevine-internal-review.googlesource.com/#/c/5353/
from the Widevine CDM repository.

Change-Id: I2d904e55d4d10eacc1a51f1c6b5c1a267c92c8d8

libwvdrmengine/cdm/core/include/timer.h

@@ -34,7 +34,7 @@ class Timer {
   Timer();
   ~Timer();
 
-  void Start(TimerHandler *handler, uint32_t time_in_secs);
+  bool Start(TimerHandler *handler, uint32_t time_in_secs);
   void Stop();
   bool IsRunning();