Tracing: disable StartupTracingThrottle, again

It is still flaky:

https://logs.chromium.org/v/?s=chromium%2Fbb%2Ftryserver.chromium.chromiumos%2Flinux-chromeos-rel%2F109818%2F%2B%2Frecipes%2Fsteps%2Fmash_browser_tests__with_patch_%2F0%2Fstdout

Bug: 832981
Change-Id: Idd9646c0bfe7ebec3c1ff9068c39d11ba02faf67
Reviewed-on: https://chromium-review.googlesource.com/1028730
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: oysteine <oysteine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553798}

chrome/browser/tracing/chrome_tracing_delegate_browsertest.cc

@@ -296,8 +296,14 @@ IN_PROC_BROWSER_TEST_F(ChromeTracingDelegateBrowserTestOnStartup,
                         base::Time::Now().ToInternalValue());
 }
 
+// https://crbug.com/832981
+#if defined(OS_CHROMEOS)
+#define MAYBE_StartupTracingThrottle DISABLED_StartupTracingThrottle
+#else
+#define MAYBE_StartupTracingThrottle StartupTracingThrottle
+#endif
 IN_PROC_BROWSER_TEST_F(ChromeTracingDelegateBrowserTestOnStartup,
-                       StartupTracingThrottle) {
+                       MAYBE_StartupTracingThrottle) {
   // The startup scenario should *not* be started, since not enough
   // time has elapsed since the last upload (set in the PRE_ above).
   EXPECT_FALSE(

testing/buildbot/filters/mash.browser_tests.filter

@@ -343,5 +343,6 @@
 -DeclarativeNetRequestResourceTypeBrowserTest.Test2/1
 -MediaEngagementSessionRestoreBrowserTest.RestoredSession_Playback_MEI
 -AutoplayExtensionBrowserTest.*
+-ChromeTracingDelegateBrowserTestOnStartup.StartupTracingThrottle
 
 # See comment at top of file regarding adding test exclusions.