[Sheriff] Disable AutoplayAllowedInIframe, which times out

AutoplayAllowedInIframe has been timing out on Linux; this CL disables
the test on that platform.

https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=browser_tests%20(with%20patch)&tests=AutoplayExtensionBrowserTest.AutoplayAllowedInIframe

R=rdevlin.cronin

Bug: 1166927
Change-Id: I8812965c620729ccf3f1252dfa27358a224dc30f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2631406
Commit-Queue: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Auto-Submit: David Van Cleve <davidvc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844050}

chrome/browser/extensions/autoplay_browsertest.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/strings/stringprintf.h"
+#include "build/build_config.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/ui/extensions/extension_action_test_helper.h"
 #include "chrome/test/base/ui_test_utils.h"
@@ -29,6 +30,13 @@ IN_PROC_BROWSER_TEST_F(AutoplayExtensionBrowserTest, AutoplayAllowed) {
   ASSERT_TRUE(RunExtensionTest("autoplay")) << message_;
 }
 
+// TODO(crbug.com/1166927): AutoplayAllowedInIframe sporadically (~10%?) times
+// out on Linux.
+#if defined(OS_LINUX)
+#define MAYBE_AutoplayAllowedInIframe DISABLED_AutoplayAllowedInIframe
+#else
+#define MAYBE_AutoplayAllowedInIframe AutoplayAllowedInIframe
+#endif  // defined(OS_LINUX)
 IN_PROC_BROWSER_TEST_F(AutoplayExtensionBrowserTest, AutoplayAllowedInIframe) {
   ASSERT_TRUE(StartEmbeddedTestServer());