chromeos: Convert D-Bus client classes' callback arguments to const reference

chromeos/dbus/cryptohome_client.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 CHROMEOS_DBUS_CRYPTOHOME_CLIENT_H_
 #define CHROMEOS_DBUS_CRYPTOHOME_CLIENT_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 33 matching lines @@
 
   // Factory function, creates a new instance and returns ownership.
   // For normal usage, access the singleton via DBusThreadManager::Get().
   static CryptohomeClient* Create(DBusClientImplementationType type,
                                   dbus::Bus* bus);
 
   // Sets AsyncCallStatus signal handler.
   // |handler| is called when results for AsyncXXX methods are returned.
   // Cryptohome service will process the calls in a first-in-first-out manner
   // when they are made in parallel.
-  virtual void SetAsyncCallStatusHandler(AsyncCallStatusHandler handler) = 0;
+  virtual void SetAsyncCallStatusHandler(
+      const AsyncCallStatusHandler& handler) = 0;
 
   // Resets AsyncCallStatus signal handler.
   virtual void ResetAsyncCallStatusHandler() = 0;
 
   // Calls IsMounted method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool IsMounted(bool* is_mounted) = 0;
 
   // Calls Unmount method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool Unmount(bool* success) = 0;
 
   // Calls AsyncCheckKey method.  |callback| is called after the method call
   // succeeds.
   virtual void AsyncCheckKey(const std::string& username,
                              const std::string& key,
-                             AsyncMethodCallback callback) = 0;
+                             const AsyncMethodCallback& callback) = 0;
 
   // Calls AsyncMigrateKey method.  |callback| is called after the method call
   // succeeds.
   virtual void AsyncMigrateKey(const std::string& username,
                                const std::string& from_key,
                                const std::string& to_key,
-                               AsyncMethodCallback callback) = 0;
+                               const AsyncMethodCallback& callback) = 0;
 
   // Calls AsyncRemove method.  |callback| is called after the method call
   // succeeds.
   virtual void AsyncRemove(const std::string& username,
-                           AsyncMethodCallback callback) = 0;
+                           const AsyncMethodCallback& callback) = 0;
 
   // Calls GetSystemSalt method.  This method blocks until the call returns.
   // The original content of |salt| is lost.
   virtual bool GetSystemSalt(std::vector<uint8>* salt) = 0;
 
   // Calls AsyncMount method.  |callback| is called after the method call
   // succeeds.
   virtual void AsyncMount(const std::string& username,
                           const std::string& key,
                           const bool create_if_missing,
-                          AsyncMethodCallback callback) = 0;
+                          const AsyncMethodCallback& callback) = 0;
 
   // Calls AsyncMountGuest method.  |callback| is called after the method call
   // succeeds.
-  virtual void AsyncMountGuest(AsyncMethodCallback callback) = 0;
+  virtual void AsyncMountGuest(const AsyncMethodCallback& callback) = 0;
 
   // Calls TpmIsReady method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool TpmIsReady(bool* ready) = 0;
 
   // Calls TpmIsEnabled method.
-  virtual void TpmIsEnabled(BoolMethodCallback callback) = 0;
+  virtual void TpmIsEnabled(const BoolMethodCallback& callback) = 0;
 
   // Calls TpmIsEnabled method and returns true when the call succeeds.
   // This method blocks until the call returns.
   // TODO(hashimoto): Remove this method. crosbug.com/28500
   virtual bool CallTpmIsEnabledAndBlock(bool* enabled) = 0;
 
   // Calls TpmGetPassword method and returns true when the call succeeds.
   // This method blocks until the call returns.
   // The original content of |password| is lost.
   virtual bool TpmGetPassword(std::string* password) = 0;
 
   // Calls TpmIsOwned method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool TpmIsOwned(bool* owned) = 0;
 
   // Calls TpmIsBeingOwned method and returns true when the call succeeds.
   // This method blocks until the call returns.
   virtual bool TpmIsBeingOwned(bool* owning) = 0;
 
   // Calls TpmCanAttemptOwnership method and returns true when the call
   // succeeds.  This method blocks until the call returns.
   virtual bool TpmCanAttemptOwnership() = 0;
 
   // Calls TpmClearStoredPassword method and returns true when the call
   // succeeds.  This method blocks until the call returns.
   virtual bool TpmClearStoredPassword() = 0;
 
   // Calls Pkcs11IsTpmTokenReady method.
-  virtual void Pkcs11IsTpmTokenReady(BoolMethodCallback callback) = 0;
+  virtual void Pkcs11IsTpmTokenReady(const BoolMethodCallback& callback) = 0;
 
   // Calls Pkcs11GetTpmTokenInfo method.
   virtual void Pkcs11GetTpmTokenInfo(
-      Pkcs11GetTpmTokenInfoCallback callback) = 0;
+      const Pkcs11GetTpmTokenInfoCallback& callback) = 0;
 
   // Calls InstallAttributesGet method and returns true when the call succeeds.
   // This method blocks until the call returns.
   // The original content of |value| is lost.
   virtual bool InstallAttributesGet(const std::string& name,
                                     std::vector<uint8>* value,
                                     bool* successful) = 0;
 
   // Calls InstallAttributesSet method and returns true when the call succeeds.
   // This method blocks until the call returns.
@@ skipping 21 matching lines @@
   // Create() should be used instead.
   CryptohomeClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CryptohomeClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_CRYPTOHOME_CLIENT_H_