Cleanup after EmbedderHeapTracer api updates

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 5429 matching lines @@
     explicit AdvanceTracingActions(ForceCompletionAction force_completion_)
         : force_completion(force_completion_) {}
 
     ForceCompletionAction force_completion;
   };
   /**
    * V8 will call this method with internal fields of found wrappers.
    * Embedder is expected to store them in it's marking deque and trace
    * reachable wrappers from them when asked by AdvanceTracing method.
    */
-  // TODO(hlopko): Make pure virtual after migration
   virtual void RegisterV8References(
-      const std::vector<std::pair<void*, void*> >& internal_fields) {}
-  /**
-   * **Deprecated**
-   */
-  // TODO(hlopko): Remove after migration
-  virtual void TraceWrappersFrom(
-      const std::vector<std::pair<void*, void*> >& internal_fields) {}
+      const std::vector<std::pair<void*, void*> >& internal_fields) = 0;
   /**
    * V8 will call this method at the beginning of the gc cycle.
    */
   virtual void TracePrologue() = 0;
   /**
    * Embedder is expected to trace its heap starting from wrappers reported by
    * RegisterV8References method, and call
    * PersistentBase::RegisterExternalReference() on all reachable wrappers.
    * Embedder is expected to stop tracing by the given deadline.
    *
    * Returns true if there is still work to do.
    */
-  // TODO(hlopko): Make pure virtual after migration
   virtual bool AdvanceTracing(double deadline_in_ms,
-                              AdvanceTracingActions actions) {
-    return false;
-  }
+                              AdvanceTracingActions actions) = 0;
   /**
    * V8 will call this method at the end of the gc cycle. Allocation is *not*
    * allowed in the TraceEpilogue.
    */
   virtual void TraceEpilogue() = 0;
 
  protected:
   virtual ~EmbedderHeapTracer() = default;
 };
 
@@ skipping 3328 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_