Introduce object visitor to estimate the size of a native context.

src/api.cc

 // 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.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
 #include <cmath>  // For isnan.
 #include "include/v8-debug.h"
 #include "include/v8-profiler.h"
 #include "include/v8-testing.h"
 #include "src/api-natives.h"
 #include "src/assert-scope.h"
 #include "src/background-parsing-task.h"
 #include "src/base/functional.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/time.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/compiler.h"
+#include "src/context-measure.h"
 #include "src/contexts.h"
 #include "src/conversions-inl.h"
 #include "src/counters.h"
 #include "src/cpu-profiler.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/execution.h"
 #include "src/global-handles.h"
 #include "src/heap/spaces.h"
 #include "src/heap-profiler.h"
@@ skipping 5535 matching lines @@
 }
 
 
 void Context::SetErrorMessageForCodeGenerationFromStrings(Local<String> error) {
   i::Handle<i::Context> context = Utils::OpenHandle(this);
   i::Handle<i::String> error_handle = Utils::OpenHandle(*error);
   context->set_error_message_for_code_gen_from_strings(*error_handle);
 }
 
 
+size_t Context::EstimatedSize() {
+  return static_cast<size_t>(
+      i::ContextMeasure(*Utils::OpenHandle(this)).Size());
+}
+
+
 MaybeLocal<v8::Object> ObjectTemplate::NewInstance(Local<Context> context) {
   PREPARE_FOR_EXECUTION(context, "v8::ObjectTemplate::NewInstance()", Object);
   auto self = Utils::OpenHandle(this);
   Local<Object> result;
   has_pending_exception =
       !ToLocal<Object>(i::ApiNatives::InstantiateObject(self), &result);
   RETURN_ON_FAILED_EXECUTION(Object);
   RETURN_ESCAPED(result);
 }
 
@@ skipping 2815 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8