Use ATRACE macros instead of Tracer statics

ATRACE_BEGIN and ATRACE_END have replaced the static
Tracer::traceBegin and Tracer::traceEnd functions, so
use them instead.

Fixes compilation errors when tracing is enabled.

Change-Id: I4d1147d2f76afcdf113e9986f0544cb848802b15
2 files changed