Disable BrowserThreadPostTaskBeforeThreadCreationBrowserTest.ExpectFailures

This test is flaky on ChromeOS.

Bug: 910834
Change-Id: I5cf214ce90aca8aafc623b526415516f52a46544
TBR: hanxi@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/1358461Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613116}

content/browser/browser_thread_browsertest.cc

@@ -5,6 +5,7 @@
 #include "base/bind_helpers.h"
 #include "base/task/post_task.h"
 #include "base/test/gtest_util.h"
+#include "build/build_config.h"
 #include "content/public/browser/browser_task_traits.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/test/content_browser_test.h"
@@ -45,7 +46,14 @@ class BrowserThreadPostTaskBeforeThreadCreationBrowserTest
   }
 };
 
+// Flaky on Chrome OS. https://crbug.com/910834
+#if defined(OS_CHROMEOS)
+#define MAYBE_ExpectFailures DISABLED_ExpectFailures
+#else
+#define MAYBE_ExpectFailures ExpectFailures
+#endif
+
 IN_PROC_BROWSER_TEST_F(BrowserThreadPostTaskBeforeThreadCreationBrowserTest,
-                       ExpectFailures) {}
+                       MAYBE_ExpectFailures) {}
 
 }  // namespace content