Remove Bluetooth adapter status UMA.

chrome/browser/signin/easy_unlock_service.cc

Index: chrome/browser/signin/easy_unlock_service.cc
diff --git a/chrome/browser/signin/easy_unlock_service.cc b/chrome/browser/signin/easy_unlock_service.cc
index 1679d3601f249b51b9d9ec1545667904eaf09239..b76ae4306b7b0859b29d7940eb635d7a363f962f 100644
--- a/chrome/browser/signin/easy_unlock_service.cc
+++ b/chrome/browser/signin/easy_unlock_service.cc
@@ -64,21 +64,10 @@
 #include "components/signin/core/account_id/account_id.h"
 #endif
 
-#if defined(OS_WIN)
-#include "base/win/windows_version.h"
-#endif
-
 using proximity_auth::ScreenlockState;
 
 namespace {
 
-enum BluetoothType {
-  BT_NO_ADAPTER,
-  BT_NORMAL,
-  BT_LOW_ENERGY_CAPABLE,
-  BT_MAX_TYPE
-};
-
 PrefService* GetLocalState() {
   return g_browser_process ? g_browser_process->local_state() : NULL;
 }
@@ -145,32 +134,17 @@ class EasyUnlockService::BluetoothDetector
     service_->OnBluetoothAdapterPresentChanged();
   }
 
-  device::BluetoothAdapter* getAdapter() {
-    return adapter_.get();
-  }
-
  private:
   void OnAdapterInitialized(scoped_refptr<device::BluetoothAdapter> adapter) {
     adapter_ = adapter;
     adapter_->AddObserver(this);
     service_->OnBluetoothAdapterPresentChanged();
 
-#if !defined(OS_CHROMEOS)
-    // Bluetooth detection causes serious performance degradations on Mac
-    // and possibly other platforms as well: http://crbug.com/467316
-    // Since this feature is currently only offered for ChromeOS we just
-    // turn it off on other platforms once the inforamtion about the
-    // adapter has been gathered and reported.
-    // TODO(bcwhite,xiyuan): Revisit when non-chromeos platforms are supported.
-    adapter_->RemoveObserver(this);
-    adapter_ = NULL;
-#else
     // TODO(tengs): At the moment, there is no way for Bluetooth discoverability
     // to be turned on except through the Easy Unlock setup. If we step on any
     // toes in the future then we need to revisit this guard.
     if (adapter_->IsDiscoverable())
       TurnOffBluetoothDiscoverability();
-#endif  // !defined(OS_CHROMEOS)
   }
 
   // apps::AppLifetimeMonitor::Observer:
@@ -744,31 +718,20 @@ void EasyUnlockService::InitializeOnAppManagerReady() {
   CHECK(app_manager_.get());
 
   InitializeInternal();
+
+#if defined(OS_CHROMEOS)
+  // Only start Bluetooth detection for ChromeOS since the feature is
+  // only offered on ChromeOS. Enabling this on non-ChromeOS platforms
+  // previously introduced a performance regression: http://crbug.com/404482
+  // Make sure not to reintroduce a performance regression if re-enabling on
+  // additional platforms.
+  // TODO(xiyuan): Revisit when non-chromeos platforms are supported.
   bluetooth_detector_->Initialize();
+#endif  // defined(OS_CHROMEOS)
 }
 
 void EasyUnlockService::OnBluetoothAdapterPresentChanged() {
   UpdateAppState();
-
-  // 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 = false;
-
-  if (!bluetooth_adapter_has_been_reported) {
-    bluetooth_adapter_has_been_reported = true;
-    int bttype = BT_NO_ADAPTER;
-    if (bluetooth_detector_->IsPresent()) {
-      bttype = BT_LOW_ENERGY_CAPABLE;
-#if defined(OS_WIN)
-      if (base::win::GetVersion() < base::win::VERSION_WIN8) {
-        bttype = BT_NORMAL;
-      }
-#endif
-    }
-    UMA_HISTOGRAM_ENUMERATION(
-      "EasyUnlock.BluetoothAvailability", bttype, BT_MAX_TYPE);
-  }
 }
 
 void EasyUnlockService::SetHardlockStateForUser(