Stop passing ReviewDb, etc. to ChangeData methods

Many methods that are intended for lazy initialization take a
ReviewDb, and some take other helper objects such as
GitRepositoryManager. This achieves the intended lazy-loading behavior
but requires a lot of injection of dependencies into callers, and may
become untenable as lazy loading of ChangeData requires more helpers.

Instead, since after all this is Java, construct ChangeData with a
Factory. This is subtle because it is used from a lot of places that
need control over which ReviewDb handle to pass in, so the factory
methods still need to take a db. ChangeData objects are still intended
(i.e. safe) for use only by one thread, so having a single ReviewDb
instance stored for the lifetime of the ChangeData should be fine. We
just need to be careful about which we pass in, particularly in a
place like ChangeIndexer.

As a side effect, clean up some other injection, particularly in the
predicate class hierarchy.

Change-Id: I52e1eb2a76788c12dd95767e89095ab80df7e1cc

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

@@ -43,14 +43,17 @@ import java.util.TreeMap;
 
 public class ReviewerJson {
   private final Provider<ReviewDb> db;
+  private final ChangeData.Factory changeDataFactory;
   private final LabelNormalizer labelNormalizer;
   private final AccountInfo.Loader.Factory accountLoaderFactory;
 
   @Inject
   ReviewerJson(Provider<ReviewDb> db,
+      ChangeData.Factory changeDataFactory,
       LabelNormalizer labelNormalizer,
       AccountInfo.Loader.Factory accountLoaderFactory) {
     this.db = db;
+    this.changeDataFactory = changeDataFactory;
     this.labelNormalizer = labelNormalizer;
     this.accountLoaderFactory = accountLoaderFactory;
   }
@@ -98,8 +101,8 @@ public class ReviewerJson {
 
     // Add dummy approvals for all permitted labels for the user even if they
     // do not exist in the DB.
-    ChangeData cd = new ChangeData(ctl);
-    PatchSet ps = cd.currentPatchSet(db);
+    ChangeData cd = changeDataFactory.create(db.get(), ctl);
+    PatchSet ps = cd.currentPatchSet();
     if (ps != null) {
       for (SubmitRecord rec :
           ctl.canSubmit(db.get(), ps, cd, true, false, true)) {