Enable FullscreenElementInABAAndExitViaEscapeKey test.

We can't access the flake log anymore, but I tested both locally and CQ dry run. The test should be stable now.

Bug: 854294
TEST: 100/100 pass locally. 100/100 pass on dry run: https://chromium-review.googlesource.com/c/chromium/src/+/1487832 https://chromium-swarm.appspot.com/task?id=433f61c47f1daa10
Change-Id: Ifc4d84b82ea7531654fd1002503d2ce91db7edaa
Reviewed-on: https://chromium-review.googlesource.com/c/1488053Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Commit-Queue: Sven Zheng <svenzheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635737}

chrome/browser/site_per_process_interactive_browsertest.cc

@@ -850,16 +850,8 @@ void SitePerProcessInteractiveBrowserTest::FullscreenElementInABA(
   EXPECT_EQ("none", GetFullscreenElementId(grandchild));
 }
 
-// This is flaky on Linux (crbug.com/854294)
-#if defined(OS_LINUX)
-#define MAYBE_FullscreenElementInABAAndExitViaEscapeKey \
-  DISABLED_FullscreenElementInABAAndExitViaEscapeKey
-#else
-#define MAYBE_FullscreenElementInABAAndExitViaEscapeKey \
-  FullscreenElementInABAAndExitViaEscapeKey
-#endif
 IN_PROC_BROWSER_TEST_F(SitePerProcessInteractiveBrowserTest,
-                       MAYBE_FullscreenElementInABAAndExitViaEscapeKey) {
+                       FullscreenElementInABAAndExitViaEscapeKey) {
   if (IsMacViewsBrowser())
     return;
   FullscreenElementInABA(FullscreenExitMethod::ESC_PRESS);