Allow InternalUsers to see drafts

According to the documentation, InternalUsers should have
full read access. This is not true, since InternalUsers cannot
see drafts.

This also means plugins utilizing the PluginUser cannot react
to events from newly created drafts.

This fix allows InternalUsers to also see draft changes
and patchsets.

Change-Id: Ibc36c3373f795cbc36535b1566a97b00dc3700ac

gerrit-server/src/main/java/com/google/gerrit/server/CurrentUser.java

@@ -100,4 +100,9 @@ public abstract class CurrentUser {
   public boolean isIdentifiedUser() {
     return false;
   }
+
+  /** Check if the CurrentUser is an InternalUser. */
+  public boolean isInternalUser() {
+    return false;
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/InternalUser.java

@@ -61,6 +61,11 @@ public class InternalUser extends CurrentUser {
     return Collections.emptySet();
   }
 
+  @Override
+  public boolean isInternalUser() {
+    return true;
+  }
+
   @Override
   public String toString() {
     return "InternalUser";

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

@@ -28,6 +28,7 @@ import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.InternalUser;
 import com.google.gerrit.server.notedb.ChangeNotes;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
@@ -352,6 +353,7 @@ public class ChangeControl {
 
   public boolean isDraftVisible(ReviewDb db, ChangeData cd)
       throws OrmException {
-    return isOwner() || isReviewer(db, cd) || getRefControl().canViewDrafts();
+    return isOwner() || isReviewer(db, cd) || getRefControl().canViewDrafts()
+        || getCurrentUser().isInternalUser();
   }
 }