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

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

Index: third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js b/third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js
index 566c9441b41d4fa12eec3f67074f1904324d81ba..2d9b050e751f6ea9d27a45cbfe8fd215fcdd17bd 100644
--- a/third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js
+++ b/third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js
@@ -387,6 +387,19 @@ InspectorTest.FakeFileReader.prototype = {
     }
 };
 
+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)