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

chromeos/dbus/mock_cros_disks_client.h

Index: chromeos/dbus/mock_cros_disks_client.h
diff --git a/chromeos/dbus/mock_cros_disks_client.h b/chromeos/dbus/mock_cros_disks_client.h
index 0b242f98e76e5d029c98793d32ba16aa0c4dec5a..b258935713bf33fc03dde19bf8455a3e173e3934 100644
--- a/chromeos/dbus/mock_cros_disks_client.h
+++ b/chromeos/dbus/mock_cros_disks_client.h
@@ -18,18 +18,25 @@ class MockCrosDisksClient : public CrosDisksClient {
   MockCrosDisksClient();
   virtual ~MockCrosDisksClient();
 
-  MOCK_METHOD4(Mount, void(const std::string&, MountType, MountCallback,
-                           ErrorCallback));
-  MOCK_METHOD3(Unmount, void(const std::string&, UnmountCallback,
-                             ErrorCallback));
-  MOCK_METHOD2(EnumerateAutoMountableDevices, void(
-      EnumerateAutoMountableDevicesCallback, ErrorCallback));
-  MOCK_METHOD4(FormatDevice, void(const std::string&, const std::string&,
-                                  FormatDeviceCallback, ErrorCallback));
-  MOCK_METHOD3(GetDeviceProperties, void(
-      const std::string&, GetDevicePropertiesCallback, ErrorCallback));
-  MOCK_METHOD2(SetUpConnections, void(MountEventHandler,
-                                      MountCompletedHandler));
+  MOCK_METHOD4(Mount, void(const std::string&,
+                           MountType,
+                           const MountCallback&,
+                           const ErrorCallback&));
+  MOCK_METHOD3(Unmount, void(const std::string&,
+                             const UnmountCallback&,
+                             const ErrorCallback&));
+  MOCK_METHOD2(EnumerateAutoMountableDevices,
+               void(const EnumerateAutoMountableDevicesCallback&,
+                    const ErrorCallback&));
+  MOCK_METHOD4(FormatDevice, void(const std::string&,
+                                  const std::string&,
+                                  const FormatDeviceCallback&,
+                                  const ErrorCallback&));
+  MOCK_METHOD3(GetDeviceProperties, void(const std::string&,
+                                         const GetDevicePropertiesCallback&,
+                                         const ErrorCallback&));
+  MOCK_METHOD2(SetUpConnections, void(const MountEventHandler&,
+                                      const MountCompletedHandler&));
 };
 
 }  // namespace chromeos