Delete an unused member variable.

Bug: None
Change-Id: I3871617f95a72eb280ed28f12926f603854e5e60
Reviewed-on: https://chromium-review.googlesource.com/c/1296618Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601996}

chrome/browser/metrics/chrome_metrics_service_client.h

@@ -194,10 +194,6 @@ class ChromeMetricsServiceClient : public metrics::MetricsServiceClient,
   // Whether we registered all notification listeners successfully.
   bool notification_listeners_active_;
 
-  // A queue of tasks for initial metrics gathering. These may be asynchronous
-  // or synchronous.
-  base::circular_deque<base::Closure> initialize_task_queue_;
-
   // Saved callback received from CollectFinalMetricsForLog().
   base::Closure collect_final_metrics_done_callback_;