Start migration to notedb implementation of PatchSetApprovals

Encapsulate the current state of the migration in a NotesMigration
class. For each database table (or broader group of functionality)
that we migrate to notedb, configure a boolean indicating whether that
data should be read from notes, defaulting to false.

Unlike reads, NotesMigration contains just a single boolean
indicating that data should be written. We don't attempt to write
just some types of data; as the migration continues we will just
rewrite history.

Since most existing reads of the PatchSetApprovals table have been
migrated to ApprovalsUtil, most implementation changes happen there.
There are a few other implementations scattered around, and some that
will require a bit more work (e.g. stamping normalized approvals at
submit time).

Change-Id: I5676267d4de607c385e8c9917a89333863b9c9e7

gerrit-server/src/main/java/com/google/gerrit/server/change/ReviewerJson.java

@@ -30,6 +30,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.account.AccountInfo;
 import com.google.gerrit.server.git.LabelNormalizer;
+import com.google.gerrit.server.notedb.ChangeNotes;
 import com.google.gerrit.server.project.ChangeControl;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
@@ -44,16 +45,19 @@ import java.util.TreeMap;
 public class ReviewerJson {
   private final Provider<ReviewDb> db;
   private final ChangeData.Factory changeDataFactory;
+  private final ApprovalsUtil approvalsUtil;
   private final LabelNormalizer labelNormalizer;
   private final AccountInfo.Loader.Factory accountLoaderFactory;
 
   @Inject
   ReviewerJson(Provider<ReviewDb> db,
       ChangeData.Factory changeDataFactory,
+      ApprovalsUtil approvalsUtil,
       LabelNormalizer labelNormalizer,
       AccountInfo.Loader.Factory accountLoaderFactory) {
     this.db = db;
     this.changeDataFactory = changeDataFactory;
+    this.approvalsUtil = approvalsUtil;
     this.labelNormalizer = labelNormalizer;
     this.accountLoaderFactory = accountLoaderFactory;
   }
@@ -75,14 +79,12 @@ public class ReviewerJson {
     return format(ImmutableList.<ReviewerResource> of(rsrc));
   }
 
-  public ReviewerInfo format(ReviewerInfo out, ChangeControl ctl,
-      List<PatchSetApproval> approvals) throws OrmException {
+  public ReviewerInfo format(ReviewerInfo out, ChangeNotes changeNotes,
+      ChangeControl ctl, List<PatchSetApproval> approvals) throws OrmException {
     PatchSet.Id psId = ctl.getChange().currentPatchSetId();
 
-    if (approvals == null) {
-      approvals = ApprovalsUtil.sortApprovals(db.get().patchSetApprovals()
-          .byPatchSetUser(psId, out._id));
-    }
+    approvals =
+        approvalsUtil.byPatchSetUser(db.get(), changeNotes, psId, out._id);
     approvals = labelNormalizer.normalize(ctl, approvals);
     LabelTypes labelTypes = ctl.getLabelTypes();
 
@@ -129,7 +131,7 @@ public class ReviewerJson {
   private ReviewerInfo format(ReviewerResource rsrc,
       List<PatchSetApproval> approvals) throws OrmException {
     return format(new ReviewerInfo(rsrc.getUser().getAccountId()),
-        rsrc.getUserControl(), approvals);
+        rsrc.getNotes(), rsrc.getUserControl(), approvals);
   }
 
   public static class ReviewerInfo extends AccountInfo {