Unify logic for validating draft deletions

This change makes validating draft deletions the same
as draft publishings.

Change-Id: I9ef00d6382c60ce28c1c002fc2c4733ac129e716

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/PatchSetComplexDisclosurePanel.java

@@ -178,13 +178,16 @@ class PatchSetComplexDisclosurePanel extends ComplexDisclosurePanel implements O
             populateActions(detail);
           }
         }
-        if (detail.getPatchSet().isDraft() && changeDetail.canPublish()) {
+        if (detail.getPatchSet().isDraft()) {
+          if (changeDetail.canPublish()) {
             populatePublishAction();
           }
-        if (canDeletePatchSet(detail)) {
+          if (changeDetail.canDeleteDraft() &&
+              changeDetail.getPatchSets().size() > 1) {
             populateDeleteDraftPatchSetAction();
           }
         }
+      }
       populateDiffAllActions(detail);
       body.add(patchTable);
 
@@ -708,17 +711,6 @@ class PatchSetComplexDisclosurePanel extends ComplexDisclosurePanel implements O
     changeScreen.update(result);
   }
 
-  private boolean canDeletePatchSet(PatchSetDetail detail) {
-    if (!detail.getPatchSet().isDraft()) {
-      return false;
-    }
-    // If the draft PS is the only one in a draft change, just delete the change.
-    if (changeDetail.getPatchSets().size() <= 1) {
-      return false;
-    }
-    return true;
-  }
-
   public PatchSet getPatchSet() {
     return patchSet;
   }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/changedetail/ChangeDetailFactory.java

@@ -124,7 +124,7 @@ public class ChangeDetailFactory extends Handler<ChangeDetail> {
     detail.setCanAbandon(change.getStatus() != Change.Status.DRAFT && change.getStatus().isOpen() && control.canAbandon());
     detail.setCanPublish(control.canPublish(db));
     detail.setCanRestore(change.getStatus() == Change.Status.ABANDONED && control.canRestore());
-    detail.setCanDeleteDraft(change.getStatus() == Change.Status.DRAFT && control.isOwner());
+    detail.setCanDeleteDraft(control.canDelete(db));
     detail.setStarred(control.getCurrentUser().getStarredChanges().contains(
         changeId));
 

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/changedetail/DeleteDraftChange.java

@@ -61,7 +61,7 @@ class DeleteDraftChange extends Handler<VoidResult> {
 
     final Change.Id changeId = patchSetId.getParentKey();
     final ChangeControl control = changeControlFactory.validateFor(changeId);
-    if (!control.isOwner()) {
+    if (!control.canDelete(db)) {
       throw new NoSuchChangeException(changeId);
     }
 

gerrit-server/src/main/java/com/google/gerrit/server/project/ChangeControl.java

@@ -189,8 +189,16 @@ public class ChangeControl {
     ;
   }
 
+  /** Can this user publish this change? */
   public boolean canPublish(final ReviewDb db) throws OrmException {
-    return isOwner() && isVisible(db);
+    return change.getStatus() == Change.Status.DRAFT && isOwner()
+        && isVisible(db);
+  }
+
+  /** Can this user delete this change? */
+  public boolean canDelete(final ReviewDb db) throws OrmException {
+    return change.getStatus() == Change.Status.DRAFT && isOwner()
+        && isVisible(db);
   }
 
   /** Can this user restore this change? */

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/ReviewCommand.java

@@ -255,7 +255,7 @@ public class ReviewCommand extends BaseCommand {
       ReviewResult result = publishDraftFactory.create(patchSetId).call();
       handleReviewResultErrors(result);
     } else if (deleteDraftPatchSet) {
-      if (changeControl.isOwner() && changeControl.isVisible(db)) {
+      if (changeControl.canDelete(db)) {
         try {
           ChangeUtil.deleteDraftPatchSet(patchSetId, gitManager, replication, patchSetInfoFactory, db);
         } catch (PatchSetInfoNotAvailableException e) {