base

Mainly fix two mistakes that I made:

1. When the ERROR_END_OF_STREAM is returned from read, the input buffer is not initialized
   release it would lead to crash

2. The mPrevTimestampUs is not initialized and thus fail in the CHECK(mPrevTimestampUs, timeUs)

Change-Id: Id1e51575fb8b3ca48e80547efd3a3a82dfac773b