[sync] Automatic bootstrapping of Sync on Win 8 from cached credentials

chrome/browser/sync/credential_cache_service_win.h

+// Copyright (c) 2012 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_SYNC_CREDENTIAL_CACHE_SERVICE_WIN_H_
+#define CHROME_BROWSER_SYNC_CREDENTIAL_CACHE_SERVICE_WIN_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
+#include "chrome/browser/profiles/profile_keyed_service.h"
+#include "chrome/browser/sync/sync_prefs.h"
+#include "chrome/common/json_pref_store.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+
+namespace base {
+class StringValue;
+class Value;
+}
+
+class Profile;
+
+namespace syncer {
+
+// On Windows 8, Chrome must maintain separate profile directories for Metro and
+// Desktop modes. When the user signs in to sync in one of the modes, we would
+// like to automatically start sync in the other mode.
+//
+// This class implements a caching service for sync credentials. It listens for
+// updates to the PrefService and TokenService that pertain to the user
+// signing in and out of sync, and persists the credentials to a separate file
+// in the default profile directory. It also contains functionality to bootstrap
+// sync using credentials that were cached due to signing in on the other
+// (alternate) mode.
+class CredentialCacheService : public ProfileKeyedService,
+                               public content::NotificationObserver,
+                               public PrefStore::Observer {
+ public:
+  explicit CredentialCacheService(Profile* profile);
+  virtual ~CredentialCacheService();
+
+  // ProfileKeyedService implementation.
+  virtual void Shutdown() OVERRIDE;
+
+  // PrefStore::Observer implementation.
+  virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
+  virtual void OnPrefValueChanged(const std::string& key) OVERRIDE;
+
+  // content::NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+ protected:
+  // Returns true if the credential cache represented by |store| contains a
+  // value for |pref_name|.
+  bool HasPref(scoped_refptr<JsonPrefStore> store,
+              const std::string& pref_name);
+
+  // Encrypts and base 64 encodes |credential|, converts the result to a
+  // StringValue, and returns the result. Caller owns the StringValue returned.
+  static base::StringValue* PackCredential(const std::string& credential);
+
+  // Extracts a string from the Value |packed|, base 64 decodes and decrypts it,
+  // and returns the result.
+  static std::string UnpackCredential(const base::Value& packed);
+
+  // Updates the value of |pref_name| to |new_value|, unless the user has signed
+  // out, in which case we write an empty string value to |pref_name|.
+  void PackAndUpdateStringPref(const std::string& pref_name,
+                              const std::string& new_value);
+
+  // Updates the value of |pref_name| to |new_value|, unless the user has signed
+  // out, in which case we write "false" to |pref_name|.
+  void UpdateBooleanPref(const std::string& pref_name, bool new_value);
+
+  // Returns the string pref value contained in |store| for |pref_name|. Assumes
+  // that |store| contains a value for |pref_name|.
+  std::string GetAndUnpackStringPref(scoped_refptr<JsonPrefStore> store,
+                                    const std::string& pref_name);
+
+  // Returns the boolean pref value contained in |store| for |pref_name|.
+  // Assumes that |store| contains a value for |pref_name|.
+  bool GetBooleanPref(scoped_refptr<JsonPrefStore> store,
+                    const std::string& pref_name);
+
+  // Getter for unit tests.
+  const scoped_refptr<JsonPrefStore>& local_store() const {
+    return local_store_;
+  }
+
+  // Setter for unit tests
+  void set_local_store(JsonPrefStore* new_local_store) {
+    local_store_ = new_local_store;
+  }
+
+ private:
+  // Returns the path to the sync credentials file in the current profile
+  // directory.
+  FilePath GetCredentialPathInCurrentProfile() const;
+
+  // Returns the path to the sync credentials file in the default Desktop
+  // profile directory if we are running in Metro mode, and vice versa.
+  FilePath GetCredentialPathInAlternateProfile() const;
+
+  // Determines if the local credential cache writer should be initialized,
+  // based on the OS version and relevant sync preferences. Returns true if the
+  // writer must be initialized, and false if not.
+  bool ShouldInitializeLocalCredentialCacheWriter() const;
+
+  // Determines if we must look for credentials in the alternate profile, based
+  // on relevant sync preferences, in addition the to conditions in
+  // ShouldInitializeLocalCredentialCacheWriter(). Returns true if we must look
+  // for cached credentials, and false if not.
+  bool ShouldLookForCachedCredentialsInAlternateProfile() const;
+
+  // Initializes the JsonPrefStore object for the local profile directory.
+  void InitializeLocalCredentialCacheWriter();
+
+  // Initializes the JsonPrefStore object for the alternate profile directory
+  // if |should_initialize| is true. We take a bool* instead of a bool since
+  // this is a callback, and base::Owned needs to clean up the flag.
+  void InitializeAlternateCredentialCacheReader(bool* should_initialize);
+
+  // Returns true if there is an empty value for kGoogleServicesUsername in the
+  // credential cache for the local profile (indicating that the user first
+  // signed in and then signed out). Returns false if there's no value at all
+  // (indicating that the user has never signed in) or if there's a non-empty
+  // value (indicating that the user is currently signed in).
+  bool HasUserSignedOut();
+
+  // Asynchronously looks for a cached credential file in the alternate profile
+  // and initiates start up using cached credentials if the file was found.
+  // Called by ProfileSyncService when it tries to start up on Windows 8 and
+  // cannot auto-start.
+  void LookForCachedCredentialsInAlternateProfile();
+
+  // Loads cached sync credentials from the alternate profile and calls
+  // ApplyCachedCredentials if the load was successful.
+  void ReadCachedCredentialsFromAlternateProfile();
+
+  // Applies the credentials read from the alternate profile to the PrefStore
+  // and TokenService of the local profile and then notifies listeners.
+  void ApplyCachedCredentials(const std::string& google_services_username,
+                              const std::string& lsid,
+                              const std::string& sid,
+                              const std::string& encryption_bootstrap_token,
+                              bool keep_everything_synced,
+                              const bool datatype_prefs[]);
+
+  // Profile for which credentials are being cached.
+  Profile* profile_;
+
+  // Used to access sync specific preferences in the PrefStore of |profile_|.
+  browser_sync::SyncPrefs sync_prefs_;
+
+  // Used for write operations to the credential cache file in the local profile
+  // directory. This is separate from the chrome pref store. Protected so that
+  // it can be accessed by unit tests.
+  scoped_refptr<JsonPrefStore> local_store_;
+
+  // Used for read operations on the credential cache file in the alternate
+  // profile directory. This is separate from the chrome pref store.
+  scoped_refptr<JsonPrefStore> alternate_store_;
+
+  // Registrar for notifications from the PrefService.
+  PrefChangeRegistrar pref_registrar_;
+
+  // Registrar for notifications from the TokenService.
+  content::NotificationRegistrar registrar_;
+
+  // WeakPtr implementation.
+  base::WeakPtrFactory<CredentialCacheService> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CredentialCacheService);
+};
+
+}  // namespace syncer
+
+#endif  // CHROME_BROWSER_SYNC_CREDENTIAL_CACHE_SERVICE_WIN_H_