Remove TRACE_JANK_REGIONS.

This was a premature optimization.  We don't need to guard it, because
the TRACE_EVENT_* macros are smart enough to avoid evaluating their args
if we're not actually tracing.

It will be good if we can use canary builds to capture traces with jank
regions.

Bug: 581518
Change-Id: I320eff45154c2d156c9c64e9877e40358b779d9d
Reviewed-on: https://chromium-review.googlesource.com/1224463Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591400}

third_party/blink/renderer/core/layout/jank_tracker.cc

@@ -62,7 +62,6 @@ static const TransformPaintPropertyNode* TransformNodeFor(
   return object.FirstFragment().LocalBorderBoxProperties().Transform();
 }
 
-#ifdef TRACE_JANK_REGIONS
 static void RegionToTracedValue(const Region& region,
                                 double granularity_scale,
                                 TracedValue& value) {
@@ -77,7 +76,6 @@ static void RegionToTracedValue(const Region& region,
   }
   value.EndArray();
 }
-#endif  // TRACE_JANK_REGIONS
 
 JankTracker::JankTracker(LocalFrameView* frame_view)
     : frame_view_(frame_view),
@@ -223,14 +221,7 @@ std::unique_ptr<TracedValue> JankTracker::PerFrameTraceData(
   value->SetDouble("jank_fraction", jank_fraction);
   value->SetDouble("cumulative_score", score_);
   value->SetDouble("max_distance", max_distance_);
-
-#ifdef TRACE_JANK_REGIONS
-  // Jank regions can be included in trace event by defining TRACE_JANK_REGIONS
-  // at the top of this file. This is useful for debugging and visualizing, but
-  // might impact performance negatively.
   RegionToTracedValue(region_, granularity_scale, *value);
-#endif
-
   value->SetBoolean("is_main_frame", frame_view_->GetFrame().IsMainFrame());
   return value;
 }