Introduce infrastructure for tracing ScriptWrappables.

third_party/WebKit/Source/bindings/core/v8/ScriptWrappableHeapTracer.cpp

+// Copyright 2016 The Chromium 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 "ScriptWrappableHeapTracer.h"
+
+#include "bindings/core/v8/ActiveScriptWrappable.h"
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/ScriptWrappableVisitor.h"
+#include "bindings/core/v8/WrapperTypeInfo.h"
+#include "platform/heap/HeapPage.h"
+
+namespace blink {
+
+ScriptWrappableHeapTracer::~ScriptWrappableHeapTracer()
+{
+}
+
+void ScriptWrappableHeapTracer::TraceRoots(v8::Isolate* isolate)
+{
+    m_tracingInProgress = true;
+    ScriptWrappableVisitor visitor(isolate, this);
+    ActiveScriptWrappable::traceActiveWrappable(&visitor);
+}
+
+void ScriptWrappableHeapTracer::AddHeaderToUnmark(HeapObjectHeader* header)
+{
+    m_headersToUnmark.push_back(header);
+}
+
+void ScriptWrappableHeapTracer::ClearTracingMarks(v8::Isolate* isolate)
+{
+    for (auto header : m_headersToUnmark)
+        header->unmarkDOM();
+
+    m_headersToUnmark.clear();
+    m_tracingInProgress = false;
+}
+
+void ScriptWrappableHeapTracer::TraceWrappableFrom(v8::Isolate* isolate, const std::vector<std::pair<void*, void*>>& hiddenFieldsOfPotentialWrappers)
+{
+    ASSERT(m_tracingInProgress);
+    for (auto pair : hiddenFieldsOfPotentialWrappers) {
+        TraceWrappableFrom(isolate, pair);
+    }
+}
+
+
+void ScriptWrappableHeapTracer::TraceWrappableFrom(v8::Isolate* isolate, std::pair<void*, void*> hiddenFields)
+{
+    if (!hiddenFields.first)
+        return;
+    if (reinterpret_cast<intptr_t>(hiddenFields.first) % 2 == 1)
+        ASSERT_NOT_REACHED();
+    if (reinterpret_cast<WrapperTypeInfo*>(hiddenFields.first)->ginEmbedder
+        != gin::GinEmbedder::kEmbedderBlink)
+        return;
+
+    ScriptWrappable* scriptWrappable = reinterpret_cast<ScriptWrappable*>(
+        hiddenFields.second);
+    uint16_t classId = scriptWrappable->wrapperTypeInfo()->wrapperClassId;
+    if (classId != WrapperTypeInfo::NodeClassId
+        && classId != WrapperTypeInfo::ObjectClassId) {
+        ASSERT_NOT_REACHED();
+        return;
+    }
+
+    ScriptWrappableVisitor visitor(isolate, this);
+    scriptWrappable->traceWrappable(&visitor);
+}
+
+void ScriptWrappableHeapTracer::TraceWrappableFrom(v8::Isolate* isolate, v8::Persistent<v8::Object>* handle)
+{
+    ScriptWrappable* scriptWrappable = toScriptWrappable(*handle);
+    uint16_t classId = scriptWrappable->wrapperTypeInfo()->wrapperClassId;
+    if (classId != WrapperTypeInfo::NodeClassId
+        && classId != WrapperTypeInfo::ObjectClassId) {
+        ASSERT_NOT_REACHED();
+        return;
+    }
+
+    ScriptWrappableVisitor visitor(isolate, this);
+    scriptWrappable->traceWrappable(&visitor);
+}
+
+}
+