Timeline: always create filmstrip model and share single instance of it

third_party/WebKit/Source/devtools/front_end/timeline/TimelineEventOverview.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 414 matching lines @@
         }
     },
 
     __proto__: WebInspector.TimelineEventOverview.prototype
 }
 
 /**
  * @constructor
  * @extends {WebInspector.TimelineEventOverview}
  * @param {!WebInspector.TimelineModel} model
- * @param {!WebInspector.TracingModel} tracingModel
+ * @param {!WebInspector.FilmStripModel} filmStripModel
  */
-WebInspector.TimelineFilmStripOverview = function(model, tracingModel)
+WebInspector.TimelineFilmStripOverview = function(model, filmStripModel)
 {
     WebInspector.TimelineEventOverview.call(this, "filmstrip", null, model);
-    this._tracingModel = tracingModel;
+    this._filmStripModel = filmStripModel;
     this.reset();
 }
 
 WebInspector.TimelineFilmStripOverview.Padding = 2;
 
 WebInspector.TimelineFilmStripOverview.prototype = {
     /**
      * @override
      */
     update: function()
     {
         WebInspector.TimelineEventOverview.prototype.update.call(this);
-        if (!this._filmStripModel)
-            return;
         var frames = this._filmStripModel.frames();
         if (!frames.length)
             return;
 
         var drawGeneration = Symbol("drawGeneration");
         this._drawGeneration = drawGeneration;
         this._imageByFrame(frames[0]).then(image => {
             if (this._drawGeneration !== drawGeneration)
                 return;
             if (!image.naturalWidth || !image.naturalHeight)
@@ skipping 31 matching lines @@
             return image.completePromise();
         }
     },
 
     /**
      * @param {number} imageWidth
      * @param {number} imageHeight
      */
     _drawFrames: function(imageWidth, imageHeight)
     {
-        if (!this._filmStripModel || !imageWidth)
+        if (!imageWidth)
             return;
         if (!this._filmStripModel.frames().length)
             return;
         var padding = WebInspector.TimelineFilmStripOverview.Padding;
         var width = this._canvas.width;
-        var zeroTime = this._tracingModel.minimumRecordTime();
-        var spanTime = this._tracingModel.maximumRecordTime() - zeroTime;
+        var zeroTime = this._filmStripModel.zeroTime();
+        var spanTime = this._filmStripModel.spanTime();
         var scale = spanTime / width;
         var context = this._canvas.getContext("2d");
         var drawGeneration = this._drawGeneration;
 
         context.beginPath();
         for (var x = padding; x < width; x += imageWidth + 2 * padding) {
             var time = zeroTime + (x + imageWidth / 2) * scale;
             var frame = this._filmStripModel.frameByTimestamp(time);
             if (!frame)
                 continue;
@@ skipping 17 matching lines @@
         }
     },
 
     /**
      * @override
      * @param {number} x
      * @return {!Promise<?Element>}
      */
     popoverElementPromise: function(x)
     {
-        if (!this._filmStripModel || !this._filmStripModel.frames().length)
+        if (!this._filmStripModel.frames().length)
             return Promise.resolve(/** @type {?Element} */ (null));
 
         var time = this._calculator.positionToTime(x);
         var frame = this._filmStripModel.frameByTimestamp(time);
         if (frame === this._lastFrame)
             return Promise.resolve(this._lastElement);
         var imagePromise = frame ? this._imageByFrame(frame) : Promise.resolve(this._emptyImage);
         return imagePromise.then(createFrameElement.bind(this));
 
         /**
@@ skipping 12 matching lines @@
         }
     },
 
     /**
      * @override
      */
     reset: function()
     {
         this._lastFrame = undefined;
         this._lastElement = null;
-        this._filmStripModel = new WebInspector.FilmStripModel(this._tracingModel);
         /** @type {!Map<!WebInspector.FilmStripModel.Frame,!Promise<!HTMLImageElement>>} */
         this._frameToImagePromise = new Map();
         this._imageWidth = 0;
     },
 
     __proto__: WebInspector.TimelineEventOverview.prototype
 }
 
 /**
  * @constructor
@@ skipping 217 matching lines @@
             counters[group] = this._quantDuration;
             this._callback(counters);
             interval -= this._quantDuration;
         }
         this._counters = [];
         this._counters[group] = interval;
         this._lastTime = time;
         this._remainder = this._quantDuration - interval;
     }
 }