Disable CrElementsInputTest.All on ChromeOS

The test is 50% flaky.

TBR=rbpotter@chromium.org

Bug: 895832
Change-Id: Ic97a551542ae757c10e81a2440454b213aa05f05
Reviewed-on: https://chromium-review.googlesource.com/c/1282959Reviewed-by: Christos Froussios <cfroussios@chromium.org>
Commit-Queue: Christos Froussios <cfroussios@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599978}

chrome/test/data/webui/cr_elements/cr_elements_focus_test.js

@@ -123,6 +123,12 @@ CrElementsInputTest.prototype = {
   ]),
 };
 
-TEST_F('CrElementsInputTest', 'All', function() {
+// This test is flaky on ChromeOS. See https://crbug.com/895832.
+GEN('#if defined(CHROME_OS)');
+GEN('#define MAYBE_All DISABLED_All');
+GEN('#else');
+GEN('#define MAYBE_All All');
+GEN('#endif');
+TEST_F('CrElementsInputTest', 'MAYBE_All', function() {
   mocha.run();
 });