Disable TabManagerTest.DiscardTabWithNonVisibleTabs on Linux.

This test has a data race; see bug for more info.

TBR=chrisha@chromium.org

Bug: 787842
Change-Id: I299403b8c4f2c2744b4c7d7a0173759bd7a65925
Reviewed-on: https://chromium-review.googlesource.com/794841Reviewed-by: Scott Little <sclittle@chromium.org>
Commit-Queue: Scott Little <sclittle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519892}

chrome/browser/resource_coordinator/tab_manager_unittest.cc

@@ -666,11 +666,18 @@ TEST_F(TabManagerTest, GetUnsortedTabStatsIsInVisibleWindow) {
   tab_strip2.CloseAllTabs();
 }
 
+// Data race on Linux. http://crbug.com/787842
+#if defined(OS_LINUX)
+#define MAYBE_DiscardTabWithNonVisibleTabs DISABLED_DiscardTabWithNonVisibleTabs
+#else
+#define MAYBE_DiscardTabWithNonVisibleTabs DiscardTabWithNonVisibleTabs
+#endif
+
 // Verify that:
 // - On ChromeOS, DiscardTab can discard every tab in a non-visible window, but
 //   cannot discard the active tab in a visible window.
 // - On other platforms, DiscardTab can discard every non-active tab.
-TEST_F(TabManagerTest, DiscardTabWithNonVisibleTabs) {
+TEST_F(TabManagerTest, MAYBE_DiscardTabWithNonVisibleTabs) {
   TabManager tab_manager;
   TabStripDummyDelegate delegate;