Oilpan: Trace ThreadState::m_gcState.
Oilpan: Trace ThreadState::m_gcState.

This patch adds tracing counter for ThreadState::m_gcState. The counter is
pretty convenient to keep track of the GC behavior.

Using TRACE_COUNTER1() for an enum value sounds a little bit like an abuse
of the tracing API, but its presentation is better than the other options...

BUG=none
R=haraken@chromium.org, keishi@chromium.org, oilpan-reviews@chromium.org

Review URL: https://codereview.chromium.org/1195323002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@197553 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk