Timeline: extract and rename TracingModelLoader into a file of its own

third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js

 var initialize_Timeline = function() {
 
 InspectorTest.preloadPanel("timeline");
 WebInspector.TempFile = InspectorTest.TempFileMock;
 
 // Scrub values when printing out these properties in the record or data field.
 InspectorTest.timelinePropertyFormatters = {
     children: "formatAsTypeName",
     endTime: "formatAsTypeName",
     requestId: "formatAsTypeName",
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     {
         return this._fileSize;
     },
 
     fileName: function()
     {
         return "fakeFile";
     }
 };
 
+InspectorTest.loadTimeline = function(timelineData)
+{
+    var timeline = WebInspector.panels.timeline;
+
+    function createFileReader(file, delegate)
+    {
+        return new InspectorTest.FakeFileReader(timelineData, delegate, timeline._saveToFile.bind(timeline));
+    }
+
+    InspectorTest.override(WebInspector.TimelineLoader, "_createFileReader", createFileReader);
+    WebInspector.TimelineLoader.loadFromFile(InspectorTest.timelineModel(), {}, new WebInspector.Progress());
+}
+
 };
 
 function generateFrames(count, callback)
 {
     makeFrame();
     function makeFrame()
     {
         document.body.style.backgroundColor = count & 1 ? "rgb(200, 200, 200)" : "rgb(240, 240, 240)";
         if (!--count) {
             callback();
             return;
         }
         if (window.testRunner)
             testRunner.capturePixelsAsyncThen(requestAnimationFrame.bind(window, makeFrame));
         else
             window.requestAnimationFrame(makeFrame);
     }
 }