Change IsMethodTracingActive to GetMethodTracingMode.

This allows traceview to tell whether tracing is active, and whether
it is sampling or method tracing.

Bug: 9968521

Change-Id: I72100d1536ea3168998110ec1cfa5a183b55a67c
(cherry picked from commit 9d3a0a2e253aecd07c4a053c19cf9b0ccaa2db49)
4 files changed