Remove unwanted header from sync_session_durations_metrics_recorder.h

SyncSessionDurationsMetricsRecorder is already ported away from
GaiaCookieManager to use IdentityManager to monitor accounts in the
Gaia cookies. This CL removes the unwanted gaia_cookie_manager_service.h
header.

Bug: 931252
Change-Id: Id1fecaaab3c74e3d9b707124e675e5e5a18d1cba
Reviewed-on: https://chromium-review.googlesource.com/c/1467361
Reviewed-by: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Abhijeet Kandalkar <abhijeet@igalia.com>
Cr-Commit-Position: refs/heads/master@{#631675}
diff --git a/components/sync/driver/sync_session_durations_metrics_recorder.h b/components/sync/driver/sync_session_durations_metrics_recorder.h
index c8139605..815a9d3 100644
--- a/components/sync/driver/sync_session_durations_metrics_recorder.h
+++ b/components/sync/driver/sync_session_durations_metrics_recorder.h
@@ -12,7 +12,6 @@
 #include "base/scoped_observer.h"
 #include "base/timer/elapsed_timer.h"
 #include "components/keyed_service/core/keyed_service.h"
-#include "components/signin/core/browser/gaia_cookie_manager_service.h"
 #include "components/sync/driver/sync_service_observer.h"
 #include "services/identity/public/cpp/identity_manager.h"