Automatically restore app data at install time

When an application being installed defines a backupAgent in its manifest, we
now automatically perform a restore of the latest-known-good data for that app.
This is defined as "data backed up by this app from this handset, if available;
otherwise data for this app as it existed when the device was initially
provisioned."  If neither option exists for the app, no restore action is
taken.

The CL involves major changes in the Backup and Package Managers...

* The Package Manager's act of installing an application has now been split
into two separate phases, with a data-restore phase optionally occurring
between these two PM actions.  First, the details of the install are performed
as usual.  Instead of immediately notifying install observers and issuing the
install-related broadcasts, the in-process install state is snapshotted and
the backup manager notified that a restore operation should be attempted.  It
does this by calling a new API on IBackupManager, passing a token by which it
identifies its in-progress install state.

The backup manager then downloads [if possible] the data for the newly-installed
application and invokes the app's backupAgent to do the restore.  After this
step, regardless of failure, it then calls back into the Package Manager to
indicate that the restore phase has been completed, supplying the token that
was passed in the original notification from the Package Manager.

The Package Manager then runs the final post-install actions: notifying install
observers and sending out all the appropriate broadcasts.  It's only at this
point that the app becomes visible to the Launcher and the rest of the OS.

... and a few other bits and pieces...

* The ApplicationInfo.backupAgentName field has been exposed to the SDK.  This
can be reverted if there's a reason to do so, but it wasn't clear that this
info needs to be hidden from 3rd party apps.

* Debug logging of restore set IDs and operation timeout tokens [used during
any asynchronous Backup Manager operation] are now consistently in hex for
readability.

* We now properly reset our binder identity before calling into the transport
during restore-set operations.  This fixes a permissions failure when a
single-app restore was attempted.

* The 'BackupTest' test app is no longer lumped onto the system partition
by default.

Change-Id: If3addefb846791f327e2a221de97c8d5d20ee7b3
diff --git a/core/java/android/content/pm/IPackageManager.aidl b/core/java/android/content/pm/IPackageManager.aidl
index 7a02a98..f793a00 100644
--- a/core/java/android/content/pm/IPackageManager.aidl
+++ b/core/java/android/content/pm/IPackageManager.aidl
@@ -154,6 +154,8 @@
     void installPackage(in Uri packageURI, IPackageInstallObserver observer, int flags,
             in String installerPackageName);
 
+    void finishPackageInstall(int token);
+
     /**
      * Delete a package.
      *