Add unit test for Decode Image event timeline data

So that we can get rid of http/tests/devtools/tracing/decode-resize.js

Bug: 1444416
Change-Id: Ia1e79d2c1143231c5851a8234866b63f0324a7ad
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/4559869
Auto-Submit: Andres Olivares <[email protected]>
Reviewed-by: Jack Franklin <[email protected]>
Commit-Queue: Andres Olivares <[email protected]>
diff --git a/test/unittests/front_end/models/timeline_model/TimelineModel_test.ts b/test/unittests/front_end/models/timeline_model/TimelineModel_test.ts
index 6f58c92..f411ca3 100644
--- a/test/unittests/front_end/models/timeline_model/TimelineModel_test.ts
+++ b/test/unittests/front_end/models/timeline_model/TimelineModel_test.ts
@@ -1425,4 +1425,18 @@
     dataForEvent.backendNodeIds.push(123 as Protocol.DOM.BackendNodeId);
     assert.strictEqual(dataForEvent, TimelineModel.TimelineModel.EventOnTimelineData.forEvent(fakeConstructedEvent));
   });
+
+  it('extracts backend node ids and image url for a Decode Image event', async () => {
+    const data = await allModelsFromFile('web-dev.json.gz');
+    const allSDKEvents = getAllTracingModelPayloadEvents(data.tracingModel);
+
+    const decodeImageEvent =
+        allSDKEvents.find(event => event.name === TraceEngine.Handlers.Types.KnownEventName.DecodeImage);
+    if (!decodeImageEvent) {
+      throw new Error('Could not find Decode Image event Event.');
+    }
+    const dataForEvent = TimelineModel.TimelineModel.EventOnTimelineData.forEvent(decodeImageEvent);
+    assert.strictEqual(dataForEvent.backendNodeIds[0], 240);
+    assert.isTrue(dataForEvent.url?.includes('.jpg'));
+  });
 });