Disable DISABLED_NavigationChainForwardBack on all platforms.

TBR: vitaliii@chromium.org
Bug: 972871
Change-Id: I5196841239ddf2ba8294457ecc7542e6843374a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1730953Reviewed-by: Sky Malice <skym@chromium.org>
Commit-Queue: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683232}

chrome/browser/sync/test/integration/single_client_sessions_sync_test.cc

@@ -480,14 +480,9 @@ IN_PROC_BROWSER_TEST_F(SingleClientSessionsSyncTest, FragmentURLNavigation) {
   WaitForURLOnServer(fragment_url);
 }
 
-// Flakily fails on mac-rel. http://crbug.com/972871
-#if defined(OS_MACOSX)
-#define MAYBE_NavigationChainForwardBack DISABLED_NavigationChainForwardBack
-#else
-#define MAYBE_NavigationChainForwardBack NavigationChainForwardBack
-#endif
+// Flakily fails on mac/linux/win. http://crbug.com/972871
 IN_PROC_BROWSER_TEST_F(SingleClientSessionsSyncTest,
-                       MAYBE_NavigationChainForwardBack) {
+                       DISABLED_NavigationChainForwardBack) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   ASSERT_TRUE(CheckInitialState(0));