Chromium doesn't compile with -Wglobal-constructors

chrome/browser/page_load_metrics/user_input_tracker.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_USER_INPUT_TRACKER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_USER_INPUT_TRACKER_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 19 matching lines @@
 // rapid succession, e.g. JS code that dispatches new navigation requests in a
 // tight loop can result in dozens of programmatically generated navigations
 // being user initiated.
 //
 // Note that UserInputTracker does not keep track of input events processed by
 // the browser, such as interactions with the Chrome browser UI (e.g. clicking
 // the 'reload' button).
 class UserInputTracker {
  public:
   // Only public for tests.
-  static const size_t kMaxTrackedEvents;
+  static constexpr size_t kMaxTrackedEvents = 100;
   static base::TimeTicks GetEventTime(const blink::WebInputEvent& event);
 
   // Given a time, round to the nearest rate-limited offset. UserInputTracker
   // rate limits events, such that at most one event will be recorded per every
   // 20ms. RoundToRateLimitedOffset round a TimeTicks down to its nearest whole
   // 20ms.
   static base::TimeTicks RoundToRateLimitedOffset(base::TimeTicks time);
 
   UserInputTracker();
   ~UserInputTracker();
@@ skipping 19 matching lines @@
 
   std::vector<base::TimeTicks> sorted_event_times_;
   base::TimeTicks most_recent_consumed_time_;
 
   DISALLOW_COPY_AND_ASSIGN(UserInputTracker);
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_USER_INPUT_TRACKER_H_