am b1d790b6: Pass null as savedState to indicate a full backup is require

 *      <!-- Use the class "MyBackupService" to perform backups for my app -->

 *      <service android:name=".MyBackupService">

 *          <intent-filter>

 *              <action android:name="android.service.action.BACKUP" />

 *              <action android:name="android.backup.BackupService.SERVICE" />

 *          </intent-filter>

 *      &lt;/service&gt;</pre>

 * 

     * IntentFilter} that accepts this action. 

     */

    @SdkConstant(SdkConstantType.SERVICE_ACTION)

    public static final String SERVICE_ACTION = "android.backup.BackupService";

    public static final String SERVICE_ACTION = "android.backup.BackupService.SERVICE";

    /**

     * The application is being asked to write any data changed since the

     * last time it performed a backup operation.  The state data recorded

     * during the last backup pass is provided in the oldStateFd file descriptor.

     * If oldState.getStatSize() is zero or negative, no old state is available

     * and the application should perform a full backup.  In both cases, a representation

     * of the final backup state after this pass should be written to the file pointed

     * to by the newStateFd file descriptor.

     * during the last backup pass is provided in the oldState file descriptor.

     * If oldState is null, no old state is available and the application should perform

     * a full backup.  In both cases, a representation of the final backup state after

     * this pass should be written to the file pointed to by the newStateFd file descriptor.

     *

     * @param oldState An open, read-only ParcelFileDescriptor pointing to the last backup

     *                 state provided by the application.  May be empty or invalid, in which

     *                 state provided by the application.  May be null, in which

     *                 case no prior state is being provided and the application should

     *                 perform a full backup.

     * @param data An open, read/write ParcelFileDescriptor pointing to the backup data

                                // one backup service per package

                                File savedStateName = new File(mStateDir,

                                        request.service.packageName);

                                File dummyName = new File(mStateDir, "#####");

                                File backupDataName = new File(mDataDir,

                                        request.service.packageName + ".data");

                                File newStateName = new File(mStateDir,

                                        request.service.packageName + ".new");

                                // In a full backup, we pass a file that is never writeable, hence

                                // is always zero-sized, as a sentinel to the callee that they must

                                // write all of their data.

                                ParcelFileDescriptor savedState = 

                                    ParcelFileDescriptor.open(

                                            (request.fullBackup) ? savedStateName : dummyName,

                                // In a full backup, we pass a null ParcelFileDescriptor as

                                // the saved-state "file"

                                ParcelFileDescriptor savedState = (request.fullBackup) ? null

                                        : ParcelFileDescriptor.open(savedStateName,

                                            ParcelFileDescriptor.MODE_READ_ONLY |

                                            ParcelFileDescriptor.MODE_CREATE);