Disable QuickOverscrollDirectionChange on CrOS

TBR=sadrul

Bug: 856079
Change-Id: If2a53d4409d22142f27fc13ebb2dfcaf82afcc54
Reviewed-on: https://chromium-review.googlesource.com/1113304Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569998}

content/browser/web_contents/web_contents_view_aura_browsertest.cc

@@ -448,7 +448,8 @@ IN_PROC_BROWSER_TEST_F(WebContentsViewAuraTest,
 
 // Disabled because the test always fails the first time it runs on the Win Aura
 // bots, and usually but not always passes second-try (See crbug.com/179532).
-#if defined(OS_WIN)
+// Flaky on CrOS as well: https://crbug.com/856079
+#if defined(OS_WIN) || defined(OS_CHROMEOS)
 #define MAYBE_QuickOverscrollDirectionChange \
         DISABLED_QuickOverscrollDirectionChange
 #else