Disable MaterialHistoryItemTest.All on chrome os

Failure here:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-rel/11980

TBR=wjmaclean@chromium.org
NOTRY=true

Bug: 669227
Change-Id: I4836948e52e9b1b2a1cbb5d6dde6b9707c27fdbc
Reviewed-on: https://chromium-review.googlesource.com/1176123Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583305}

chrome/test/data/webui/md_history/md_history_browsertest.js

@@ -98,7 +98,7 @@ MaterialHistoryListTest.prototype = {
 
 // Times out on debug builders because the History page can take several seconds
 // to load in a Debug build. See https://crbug.com/669227.
-GEN('#if !defined(NDEBUG) || defined(OS_MACOSX)');
+GEN('#if !defined(NDEBUG) || defined(OS_MACOSX) || defined(OS_CHROMEOS)');
 GEN('#define MAYBE_All DISABLED_All');
 GEN('#else');
 GEN('#define MAYBE_All All');