[Cleanup] Clean up Easy Unlock code a bit.

chrome/browser/signin/easy_unlock_service.cc

 // 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.
 
 #include "chrome/browser/signin/easy_unlock_service.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 295 matching lines @@
   if (!bluetooth_detector_->IsPresent())
     return false;
 
   return true;
 #else
   // TODO(xiyuan): Revisit when non-chromeos platforms are supported.
   return false;
 #endif
 }
 
+bool EasyUnlockService::IsEnabled() const {
+  // The feature is enabled iff there are any paired devices.
+  const base::ListValue* devices = GetRemoteDevices();
+  return devices && !devices->empty();
+}
+
 void EasyUnlockService::SetHardlockState(
     EasyUnlockScreenlockStateHandler::HardlockState state) {
   const std::string user_id = GetUserEmail();
   if (user_id.empty())
     return;
 
   SetHardlockStateForUser(user_id, state);
 }
 
 EasyUnlockScreenlockStateHandler::HardlockState
@@ skipping 430 matching lines @@
 
   // TODO(tbarzic): Set check_private_key only if previous sign-in attempt
   // failed.
   EasyUnlockTpmKeyManagerFactory::GetInstance()->Get(profile_)
       ->PrepareTpmKey(true /* check_private_key */,
                       base::Closure());
 #endif  // defined(OS_CHROMEOS)
 
   tpm_key_checked_ = true;
 }