DevTools: introduce "Track CSS Usage" experiment

third_party/WebKit/Source/devtools/front_end/main/Main.js

Index: third_party/WebKit/Source/devtools/front_end/main/Main.js
diff --git a/third_party/WebKit/Source/devtools/front_end/main/Main.js b/third_party/WebKit/Source/devtools/front_end/main/Main.js
index 63857cd80deda28b0936860fa440bd8eb1605c1c..8ef7dfcba795e64cb2f75224ef9c55705b300519 100644
--- a/third_party/WebKit/Source/devtools/front_end/main/Main.js
+++ b/third_party/WebKit/Source/devtools/front_end/main/Main.js
@@ -126,6 +126,7 @@ WebInspector.Main = class {
     Runtime.experiments.register('timelineRecordingPerspectives', 'Timeline recording perspectives UI');
     Runtime.experiments.register('timelineTracingJSProfile', 'Timeline tracing based JS profiler', true);
     Runtime.experiments.register('timelineV8RuntimeCallStats', 'V8 Runtime Call Stats on Timeline', true);
+    Runtime.experiments.register('timelineRuleUsageRecording', 'Timeline tracing the CSS rule usage');

[caseq, 2016/11/04 21:10:02]

Track CSS rules usage while recording Timeline.

 
     Runtime.experiments.cleanUpStaleExperiments();
 
@@ -1066,3 +1067,4 @@ WebInspector.ShowMetricsRulersSettingUI = class {
 };
 
 new WebInspector.Main();
+

[caseq, 2016/11/04 21:10:02]

revert this line.