Report Bluetooth adapter status to UMA.

chrome/browser/signin/easy_unlock_service.h

 // Copyright 2014 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_SIGNIN_EASY_UNLOCK_SERVICE_H_
 #define CHROME_BROWSER_SIGNIN_EASY_UNLOCK_SERVICE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 313 matching lines @@
 
   // Whether the service has been shut down.
   bool shut_down_;
 
   bool tpm_key_checked_;
 
   ObserverList<EasyUnlockServiceObserver> observers_;
 
   base::WeakPtrFactory<EasyUnlockService> weak_ptr_factory_;
 
+  // Whether we've already passed Bluetooth availability information to UMA.
+  // This is static because there may be multiple instances and we want to
+  // report this system-level stat only once per run of Chrome.
+  static bool bluetooth_adapter_has_been_reported;

[xiyuan, 2015/03/20 19:19:31]

How about declare this flag as a function scoped static var inside
EasyUnlockService::OnBluetoothAdapterPresentChanged?

[bcwhite, 2015/03/20 20:28:26]

Makes sense.  Done.

+
   DISALLOW_COPY_AND_ASSIGN(EasyUnlockService);
 };
 
 #endif  // CHROME_BROWSER_SIGNIN_EASY_UNLOCK_SERVICE_H_