Timeline: check category presence in list, not string equality

Source/devtools/front_end/components_lazy/FilmStripModel.js

Index: Source/devtools/front_end/components_lazy/FilmStripModel.js
diff --git a/Source/devtools/front_end/components_lazy/FilmStripModel.js b/Source/devtools/front_end/components_lazy/FilmStripModel.js
index 88bec4badddc146f8882207cfe41c8ad3e880c9f..40f4aa1982684d7a701f7f96df9f5cc55a897d40 100644
--- a/Source/devtools/front_end/components_lazy/FilmStripModel.js
+++ b/Source/devtools/front_end/components_lazy/FilmStripModel.js
@@ -24,7 +24,7 @@ WebInspector.FilmStripModel = function(tracingModel)
 
     var events = mainThread.events();
     for (var i = 0; i < events.length; ++i) {
-        if (events[i].category !== "disabled-by-default-devtools.screenshot")
+        if (!events[i].hasCategory(WebInspector.FilmStripModel._category))
             continue;
 
         if (events[i].name === WebInspector.FilmStripModel.TraceEvents.CaptureFrame) {
@@ -37,6 +37,8 @@ WebInspector.FilmStripModel = function(tracingModel)
     }
 }
 
+WebInspector.FilmStripModel._category = "disabled-by-default-devtools.screenshot";
+
 WebInspector.FilmStripModel.TraceEvents = {
     CaptureFrame: "CaptureFrame",
     Screenshot: "Screenshot"