Add some more codecs to execution-phase SkyKeys.

PiperOrigin-RevId: 185883201
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ActionTemplateExpansionValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/ActionTemplateExpansionValue.java
index b8feb28..8ba11ee 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ActionTemplateExpansionValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ActionTemplateExpansionValue.java
@@ -21,6 +21,8 @@
 import com.google.devtools.build.lib.actions.ActionLookupValue;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
+import com.google.devtools.build.lib.skyframe.serialization.ObjectCodec;
+import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
 import com.google.devtools.build.skyframe.SkyFunctionName;
 
 /**
@@ -34,14 +36,17 @@
     super(actionKeyContext, ImmutableList.copyOf(expandedActions), removeActionsAfterEvaluation);
   }
 
-  private static final Interner<ActionTemplateExpansionKey> interner =
-      BlazeInterners.newWeakInterner();
-
   static ActionTemplateExpansionKey key(ActionLookupKey actionLookupKey, int actionIndex) {
-    return interner.intern(new ActionTemplateExpansionKey(actionLookupKey, actionIndex));
+    return ActionTemplateExpansionKey.of(actionLookupKey, actionIndex);
   }
 
+  @AutoCodec
   static final class ActionTemplateExpansionKey extends ActionLookupKey {
+    static final ObjectCodec<ActionTemplateExpansionKey> CODEC =
+        new ActionTemplateExpansionValue_ActionTemplateExpansionKey_AutoCodec();
+    private static final Interner<ActionTemplateExpansionKey> interner =
+        BlazeInterners.newWeakInterner();
+
     private final ActionLookupKey actionLookupKey;
     private final int actionIndex;
 
@@ -50,6 +55,12 @@
       this.actionIndex = actionIndex;
     }
 
+    @AutoCodec.VisibleForSerialization
+    @AutoCodec.Instantiator
+    static ActionTemplateExpansionKey of(ActionLookupKey actionLookupKey, int actionIndex) {
+      return interner.intern(new ActionTemplateExpansionKey(actionLookupKey, actionIndex));
+    }
+
     @Override
     public SkyFunctionName functionName() {
       return SkyFunctions.ACTION_TEMPLATE_EXPANSION;