Support for handling TreeArtifact metadata and returning TreeArtifacts from ArtifactFunction.

--
MOS_MIGRATED_REVID=114174899
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/FilesystemValueCheckerTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/FilesystemValueCheckerTest.java
index 95cb020..d695780 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/FilesystemValueCheckerTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/FilesystemValueCheckerTest.java
@@ -453,12 +453,16 @@
         Path path = output.getPath();
         FileStatusWithDigest stat =
             forceDigest ? statWithDigest(path, path.statIfFound(Symlinks.NOFOLLOW)) : null;
-        artifactData.put(output, ActionMetadataHandler.fileValueFromArtifact(output, stat, tsgm));
+        artifactData.put(output,
+            ActionMetadataHandler.fileValueFromArtifactFile(output, stat, tsgm));
       } catch (IOException e) {
         throw new IllegalStateException(e);
       }
     }
-    return new ActionExecutionValue(artifactData, ImmutableMap.<Artifact, FileArtifactValue>of());
+    return new ActionExecutionValue(
+        artifactData,
+        ImmutableMap.<Artifact, TreeArtifactValue>of(),
+        ImmutableMap.<Artifact, FileArtifactValue>of());
   }
 
   @Test