Enable BrowserKeyEventsTest.ReservedAccelerators on Linux.

It doesn't appear to flake on desktop Linux or Chrome OS (ash or mash).

Bug: 69475
Change-Id: I6bebb08d7dd1bca61cc952eb58105eab0d67a1c4
Reviewed-on: https://chromium-review.googlesource.com/c/1327148
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607366}

chrome/browser/browser_keyevents_browsertest.cc

@@ -633,13 +633,7 @@ IN_PROC_BROWSER_TEST_F(BrowserKeyEventsTest, MAYBE_AccessKeys) {
   EXPECT_NO_FATAL_FAILURE(CheckFocusedElement(tab_index, L""));
 }
 
-// Flaky, http://crbug.com/69475.
-#if defined(OS_LINUX)
-#define MAYBE_ReservedAccelerators DISABLED_ReservedAccelerators
-#else
-#define MAYBE_ReservedAccelerators ReservedAccelerators
-#endif
-IN_PROC_BROWSER_TEST_F(BrowserKeyEventsTest, MAYBE_ReservedAccelerators) {
+IN_PROC_BROWSER_TEST_F(BrowserKeyEventsTest, ReservedAccelerators) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ASSERT_TRUE(ui_test_utils::BringBrowserWindowToFront(browser()));