cros: Implement cryptohome backend for pin.

chrome/browser/chromeos/login/quick_unlock/pin_storage_prefs.h

 // Copyright 2016 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_CHROMEOS_LOGIN_QUICK_UNLOCK_PIN_STORAGE_H_
-#define CHROME_BROWSER_CHROMEOS_LOGIN_QUICK_UNLOCK_PIN_STORAGE_H_
+#ifndef CHROME_BROWSER_CHROMEOS_LOGIN_QUICK_UNLOCK_PIN_STORAGE_PREFS_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_QUICK_UNLOCK_PIN_STORAGE_PREFS_H_
 
 #include <string>
 
-#include "base/gtest_prod_util.h"
-#include "base/time/time.h"
+#include "base/macros.h"
 
 class PrefRegistrySimple;
-class PrefService;
+class Profile;
 
 namespace chromeos {
 
 class PinStorageTestApi;
 
 namespace quick_unlock {
 
 class QuickUnlockStorage;
 
-class PinStorage {
+class PinStoragePrefs {
  public:
-  // TODO(sammiequon): Pull this value in from policy. See crbug.com/612271.
   static const int kMaximumUnlockAttempts = 3;
 
   // Registers profile prefs.
   static void RegisterProfilePrefs(PrefRegistrySimple* registry);
 
-  explicit PinStorage(PrefService* pref_service);
-  ~PinStorage();
-
-  // Add a PIN unlock attempt count.
-  void AddUnlockAttempt();
-  // Reset the number of unlock attempts to 0.
-  void ResetUnlockAttemptCount();
-  // Returns the number of unlock attempts.
-  int unlock_attempt_count() const { return unlock_attempt_count_; }
+  explicit PinStoragePrefs(Profile* profile);
+  ~PinStoragePrefs();
 
   // Returns true if a pin is set.
   bool IsPinSet() const;
-  // Sets the pin to the given value; IsPinSet will return true.
+
+  // Sets the pin to the given value.
   void SetPin(const std::string& pin);
+
   // Removes the pin; IsPinSet will return false.
   void RemovePin();
 
- private:
-  friend class chromeos::PinStorageTestApi;
-  friend class QuickUnlockStorage;
-
   // Is PIN entry currently available?
   bool IsPinAuthenticationAvailable() const;
 
   // Tries to authenticate the given pin. This will consume an unlock attempt.
   // This always returns false if IsPinAuthenticationAvailable returns false.
+  //
+  // This is a no-op for cryptohome implementation (standard password flow works
+  // there).
   bool TryAuthenticatePin(const std::string& pin);
 
+  // Implementation should return true if it needs strong auth support, ie, the
+  // user has to type their password every x hours.
+  bool NeedsStrongAuth() const;
+
+  // Add a PIN unlock attempt count.
+  void AddUnlockAttempt();
+
+  // Reset the unlock attempt count to 0. Not applicable to all implementations.
+  void ResetUnlockAttemptCount();
+
+  // Returns the number of unlock attempts.
+  int unlock_attempt_count() const { return unlock_attempt_count_; }
+
+ private:
+  friend class chromeos::PinStorageTestApi;
+  friend class QuickUnlockStorage;
+
   // Return the stored salt/secret. This is fetched directly from pref_service_.
   std::string PinSalt() const;
   std::string PinSecret() const;
 
-  PrefService* pref_service_;
+  Profile* profile_;
   int unlock_attempt_count_ = 0;
 
-  DISALLOW_COPY_AND_ASSIGN(PinStorage);
+  DISALLOW_COPY_AND_ASSIGN(PinStoragePrefs);
 };
 
 }  // namespace quick_unlock
 }  // namespace chromeos
 
-#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_QUICK_UNLOCK_PIN_STORAGE_H_
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_QUICK_UNLOCK_PIN_STORAGE_PREFS_H_