Don't enqueue allowBackup=false apps for full backup attempts

We are correctly refusing to actually process apps for backup if they have
declared android:allowBackup="false" in their manifests, but we're still
wasting bookkeeping & a certain amount of work in tracking them as part of
the full backup queue.  Fix that; now we recognize that they shouldn't be
in the queue in the first place.

When reinflating the queue at boot time we also re-verify the participation
of each mentioned app so that we properly drop ones that have been uninstalled
or altered such that they are no longer full-data backup candidates.

Finally, if an app previously implemented key/value backup, so we think
we'll be running it in that mode in a future backup pass, but has been
updated to use the full-data path instead, we don't want to go ahead and
run a key/value pass on it.  Added a backstop check and proceed gracefully
in this situation.

(Also add bit more debug-build logging to LocalTransport)

Bug 19462310

Change-Id: I07ab4f2e68e92766d9e8f2595fa763c91193d743
diff --git a/core/java/com/android/internal/backup/LocalTransport.java b/core/java/com/android/internal/backup/LocalTransport.java
index c3cc60a..fb0ffb0 100644
--- a/core/java/com/android/internal/backup/LocalTransport.java
+++ b/core/java/com/android/internal/backup/LocalTransport.java
@@ -369,6 +369,9 @@
                 return TRANSPORT_ERROR;
             }
         }
+        if (DEBUG) {
+            Log.v(TAG, "   stored " + numBytes + " of data");
+        }
         return TRANSPORT_OK;
     }
 
@@ -431,6 +434,10 @@
 
     @Override
     public RestoreDescription nextRestorePackage() {
+        if (DEBUG) {
+            Log.v(TAG, "nextRestorePackage() : mRestorePackage=" + mRestorePackage
+                    + " length=" + mRestorePackages.length);
+        }
         if (mRestorePackages == null) throw new IllegalStateException("startRestore not called");
 
         boolean found = false;
@@ -441,7 +448,10 @@
             // skip packages where we have a data dir but no actual contents
             String[] contents = (new File(mRestoreSetIncrementalDir, name)).list();
             if (contents != null && contents.length > 0) {
-                if (DEBUG) Log.v(TAG, "  nextRestorePackage(TYPE_KEY_VALUE) = " + name);
+                if (DEBUG) {
+                    Log.v(TAG, "  nextRestorePackage(TYPE_KEY_VALUE) @ "
+                        + mRestorePackage + " = " + name);
+                }
                 mRestoreType = RestoreDescription.TYPE_KEY_VALUE;
                 found = true;
             }
@@ -450,7 +460,10 @@
                 // No key/value data; check for [non-empty] full data
                 File maybeFullData = new File(mRestoreSetFullDir, name);
                 if (maybeFullData.length() > 0) {
-                    if (DEBUG) Log.v(TAG, "  nextRestorePackage(TYPE_FULL_STREAM) = " + name);
+                    if (DEBUG) {
+                        Log.v(TAG, "  nextRestorePackage(TYPE_FULL_STREAM) @ "
+                                + mRestorePackage + " = " + name);
+                    }
                     mRestoreType = RestoreDescription.TYPE_FULL_STREAM;
                     mCurFullRestoreStream = null;   // ensure starting from the ground state
                     found = true;
@@ -460,6 +473,11 @@
             if (found) {
                 return new RestoreDescription(name, mRestoreType);
             }
+
+            if (DEBUG) {
+                Log.v(TAG, "  ... package @ " + mRestorePackage + " = " + name
+                        + " has no data; skipping");
+            }
         }
 
         if (DEBUG) Log.v(TAG, "  no more packages to restore");