[Extensions] Add a TODO for a disabled test.

Bug: 1028308
Change-Id: I95a678b69836418fb47c9bef3351653c4078329e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2268303Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Commit-Queue: David Bertoni <dbertoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782739}

chrome/browser/extensions/execute_script_apitest.cc

@@ -156,6 +156,7 @@ IN_PROC_BROWSER_TEST_P(DestructiveScriptTest, MicrotaskRemoval) {
   ASSERT_TRUE(RunSubtest("microtask")) << message_;
 }
 
+// TODO(http://crbug.com/1028308): Flaky on multiple platforms
 // Removes the frame at the frame's first scheduled macrotask.
 IN_PROC_BROWSER_TEST_P(DestructiveScriptTest, DISABLED_MacrotaskRemoval) {
   ASSERT_TRUE(RunSubtest("macrotask")) << message_;