[sheriff] Disable RenderWidgetHostViewAuraOverscrollTest.ReverseFlingCancelsOverscroll

This CL disables the test on Cast Audio Linux.

TBR=treib@chromium.org
NOTRY=true

Bug: 810690
Change-Id: I76214c00dd73a0874abf0afa5fff6a3a8d039fb2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2237710Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776523}

content/browser/renderer_host/render_widget_host_view_aura_unittest.cc

@@ -3838,7 +3838,7 @@ TEST_F(RenderWidgetHostViewAuraOverscrollTest,
 // Tests that a fling in the opposite direction of the overscroll cancels the
 // overscroll instead of completing it.
 // Flaky on Fuchsia:  http://crbug.com/810690.
-#if defined(OS_FUCHSIA)
+#if defined(OS_FUCHSIA) || defined(OS_LINUX)
 #define MAYBE_ReverseFlingCancelsOverscroll \
   DISABLED_ReverseFlingCancelsOverscroll
 #else