Add a stub for SyntheticItems#getSynthesizingContexts()

Bug: 180091213
Change-Id: I237b15e34a9e99d1457b18cfdd2ad0c9f95139f3
diff --git a/src/main/java/com/android/tools/r8/synthesis/SyntheticItems.java b/src/main/java/com/android/tools/r8/synthesis/SyntheticItems.java
index 6c07af2..73b61b3 100644
--- a/src/main/java/com/android/tools/r8/synthesis/SyntheticItems.java
+++ b/src/main/java/com/android/tools/r8/synthesis/SyntheticItems.java
@@ -4,7 +4,6 @@
 package com.android.tools.r8.synthesis;
 
 import com.android.tools.r8.contexts.CompilationContext.UniqueContext;
-import com.android.tools.r8.errors.InternalCompilerError;
 import com.android.tools.r8.graph.AppInfo;
 import com.android.tools.r8.graph.AppView;
 import com.android.tools.r8.graph.DexApplication;
@@ -12,6 +11,7 @@
 import com.android.tools.r8.graph.DexClasspathClass;
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.graph.DexProgramClass;
+import com.android.tools.r8.graph.DexReference;
 import com.android.tools.r8.graph.DexType;
 import com.android.tools.r8.graph.GraphLens.NonIdentityGraphLens;
 import com.android.tools.r8.graph.ProgramDefinition;
@@ -137,16 +137,6 @@
     appView.setAppInfo(new AppInfo(commit, appView.appInfo().getMainDexInfo()));
   }
 
-  // Internal synthetic id creation helpers.
-
-  private synchronized String getNextSyntheticId() {
-    if (nextSyntheticId == INVALID_ID_AFTER_SYNTHETIC_FINALIZATION) {
-      throw new InternalCompilerError(
-          "Unexpected attempt to synthesize classes after synthetic finalization.");
-    }
-    return Integer.toString(nextSyntheticId++);
-  }
-
   // Predicates and accessors.
 
   @Override
@@ -225,6 +215,13 @@
     return isSyntheticClass(clazz.type);
   }
 
+  // TODO(b/180091213): Implement this and remove client provided the oracle.
+  public Set<DexReference> getSynthesizingContexts(
+      DexProgramClass clazz, Function<DexProgramClass, Set<DexReference>> oracle) {
+    assert isSyntheticClass(clazz);
+    return oracle.apply(clazz);
+  }
+
   // The compiler should not inspect the kind of a synthetic, so this provided only as a assertion
   // utility.
   public boolean verifySyntheticLambdaProperty(