[CrOS Tether]: Add LocalDeviceDataProvider, which fetches device data for the local device.

components/cryptauth/cryptauth_enrollment_manager.h

 // Copyright 2015 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 COMPONENTS_PROXIMITY_AUTH_CRYPTAUTH_CRYPTAUTH_ENROLLMENT_MANAGER_H
 #define COMPONENTS_PROXIMITY_AUTH_CRYPTAUTH_CRYPTAUTH_ENROLLMENT_MANAGER_H
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 94 matching lines @@
 
   // Returns true if the last enrollment failed and the manager is now
   // scheduling enrollments more aggressively to recover. If no enrollment has
   // ever been recorded, then this function will also return true.
   bool IsRecoveringFromFailure() const;
 
   // Returns the keypair used to enroll with CryptAuth. If no enrollment has
   // been completed, then an empty string will be returned.
   // Note: These keys are really serialized protocol buffer messages, and should
   // only be used by passing to SecureMessageDelegate.
-  std::string GetUserPublicKey();
-  std::string GetUserPrivateKey();
+  std::string GetUserPublicKey() const;
+  std::string GetUserPrivateKey() const;
 
  protected:
   // Creates a new SyncScheduler instance. Exposed for testing.
   virtual std::unique_ptr<SyncScheduler> CreateSyncScheduler();
 
  private:
   // CryptAuthGCMManager::Observer:
   void OnGCMRegistrationResult(bool success) override;
   void OnReenrollMessage() override;
 
@@ skipping 53 matching lines @@
   base::ObserverList<Observer> observers_;
 
   base::WeakPtrFactory<CryptAuthEnrollmentManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CryptAuthEnrollmentManager);
 };
 
 }  // namespace cryptauth
 
 #endif  // COMPONENTS_PROXIMITY_CRYPTAUTH_CRYPTAUTH_ENROLLMENT_MANAGER_H