[ESLint] Fix violations when enabling curly rule in eslint.

tracing/tracing/metrics/blink/gc_metric.html

Index: tracing/tracing/metrics/blink/gc_metric.html
diff --git a/tracing/tracing/metrics/blink/gc_metric.html b/tracing/tracing/metrics/blink/gc_metric.html
index 0507869591906af08bd8f8b01a86bd4947b0b550..c1b036a0b9ebda439345851071b43747120c9b76 100644
--- a/tracing/tracing/metrics/blink/gc_metric.html
+++ b/tracing/tracing/metrics/blink/gc_metric.html
@@ -80,10 +80,11 @@ tr.exportTo('tr.metrics.blink', function() {
 
   function createPercentage(name, numerator, denominator) {
     var histogram = new tr.v.Histogram(name, percentage_biggerIsBetter);
-    if (denominator === 0)
+    if (denominator === 0) {
       histogram.addSample(0);
-    else
+    } else {
       histogram.addSample(numerator / denominator);
+    }
     return histogram;
   }