Use random URLs in tracing layout tests to avoid caching

third_party/WebKit/LayoutTests/http/tests/inspector/tracing/timeline-receive-response-event.html

Index: third_party/WebKit/LayoutTests/http/tests/inspector/tracing/timeline-receive-response-event.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/inspector/tracing/timeline-receive-response-event.html b/third_party/WebKit/LayoutTests/http/tests/inspector/tracing/timeline-receive-response-event.html
index c20c40a9bb05c90045061eb6765ed79b361e6bcb..7ec12516b49d5a1e0b65308f7e9958298c7933d3 100644
--- a/third_party/WebKit/LayoutTests/http/tests/inspector/tracing/timeline-receive-response-event.html
+++ b/third_party/WebKit/LayoutTests/http/tests/inspector/tracing/timeline-receive-response-event.html
@@ -10,13 +10,15 @@ function performActions()
     var promise = new Promise((fulfill) => callback = fulfill);
     var image = new Image();
     image.onload = bar;
-    image.src = "resources/anImage.png";
+    // Use random urls to avoid caching.
+    const random = Math.random();
+    image.src = "resources/anImage.png?random=" + random;
 
     function bar()
     {
         var image = new Image();
         image.onload = function(event) { callback(); }  // do not pass event argument to the callback.
-        image.src = "resources/anotherImage.png";
+        image.src = "resources/anotherImage.png?random=" + random;
     }
     return promise;
 }