Merge change 1217 into donut

* changes:
  Sketch out the IBackupTransport api

core/java/com/android/internal/backup/IBackupTransport.aidl

@@ -16,6 +16,54 @@
 
 package com.android.internal.backup;
 
+import android.os.ParcelFileDescriptor;
+
 /** {@hide} */
 interface IBackupTransport {
+/* STOPSHIP - don't ship with this comment in place
+    Things the transport interface has to do:
+    1. set up the connection to the destination
+        - set up encryption
+        - for Google cloud, log in using the user's gaia credential or whatever
+        - for sd, spin off the backup transport and establish communication with it
+    2. send each app's backup transaction
+        - parse the data file for key/value pointers etc
+        - send key/blobsize set to the Google cloud, get back quota ok/rejected response
+        - sd/adb doesn't preflight; no per-app quota
+        - app's entire change is essentially atomic
+        - cloud transaction encrypts then sends each key/value pair separately; we already
+          parsed the data when preflighting so we don't have to again here
+        - sd target streams raw data into encryption envelope then to sd?
+    3. shut down connection to destination
+        - cloud: tear down connection etc
+        - sd: close the file and shut down the writer proxy
+*/
+    /**
+     * Establish a connection to the back-end data repository, if necessary.  If the transport
+     * needs to initialize state that is not tied to individual applications' backup operations,
+     * this is where it should be done.
+     *
+     * @return Zero on success; a nonzero error code on failure.
+     */
+    int startSession();
+
+    /**
+     * Send one application's data to the backup destination.
+     *
+     * @param packageName The identity of the application whose data is being backed up.
+     * @param data The data stream that resulted from invoking the application's
+     *        BackupService.doBackup() method.  This may be a pipe rather than a
+     *        file on persistent media, so it may not be seekable.
+     * @return Zero on success; a nonzero error code on failure.
+     */
+    int performBackup(String packageName, in ParcelFileDescriptor data);
+
+    /**
+     * Terminate the backup session, closing files, freeing memory, and cleaning up whatever
+     * other state the transport required.
+     *
+     * @return Zero on success; a nonzero error code on failure.  Even on failure, the session
+     *         is torn down and must be restarted if another backup is attempted.
+     */
+    int endSession();
 }