Report Bluetooth adapter status to UMA.

chrome/browser/signin/easy_unlock_service.h

Index: chrome/browser/signin/easy_unlock_service.h
diff --git a/chrome/browser/signin/easy_unlock_service.h b/chrome/browser/signin/easy_unlock_service.h
index 8500446d1cec3b34ec751e7aca6170bb60d3f582..deff0917fccec3fc6314751b86cde1a3a2f2ae04 100644
--- a/chrome/browser/signin/easy_unlock_service.h
+++ b/chrome/browser/signin/easy_unlock_service.h
@@ -331,6 +331,11 @@ class EasyUnlockService : public KeyedService {
 
   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);
 };