Re-enable MergeSessionTest.Throttle

The underlying issue that has been causing many flakes here
(https://crbug.com/1005082) has been fixed, so re-enable the
browsertest.

Bug: 1005084
Change-Id: I0147578787ca11d8ddbfd49158dfc5eda5bf8a36
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1821482Reviewed-by: Chris Mumford <cmumford@google.com>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Commit-Queue: Pavol Marko <pmarko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699723}

chrome/browser/chromeos/login/signin/oauth2_browsertest.cc

@@ -17,7 +17,6 @@
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/task/post_task.h"
-#include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/login/existing_user_controller.h"
@@ -1030,13 +1029,7 @@ IN_PROC_BROWSER_TEST_P(MergeSessionTest, PageThrottle) {
   DVLOG(1) << "Loaded page at the end : " << title;
 }
 
-// TODO(crbug.com/1005084) Disabled on Chrome OS due to timeouts
-#if defined(OS_CHROMEOS)
-#define MAYBE_XHRThrottle DISABLED_XHRThrottle
-#else
-#define MAYBE_XHRThrottle XHRThrottle
-#endif
-IN_PROC_BROWSER_TEST_P(MergeSessionTest, MAYBE_XHRThrottle) {
+IN_PROC_BROWSER_TEST_P(MergeSessionTest, Throttle) {
   StartNewUserSession(/*wait_for_merge=*/false,
                       /*is_under_advanced_protection=*/false);