[Bindings] Create and use V8 context snapshots

third_party/WebKit/Source/bindings/core/v8/V8ContextSnapshot.h

+// Copyright 2017 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.
+
+#ifndef V8ContextSnapshot_h
+#define V8ContextSnapshot_h
+
+#include "core/CoreExport.h"
+#include "platform/wtf/Allocator.h"
+#include "v8/include/v8.h"
+
+namespace blink {
+
+class Document;
+class DOMWrapperWorld;
+
+// This class contains helper functions to take and use a V8 context snapshot.
+//
+// The V8 context snapshot is taken by tools/v8_context_snapshot/ when Chromium
+// is built, and is used when Blink creates a new V8 context. When to build or
+// to use the V8 context snapshot, you have a table of references of C++
+// callbacks exposed to V8.
+//
+// A V8 context snapshot contains:
+// - Interface templates of Window, EventTarget, Node, Document, and
+//   HTMLDocument.
+// - Two types of V8 contexts; one is for the main world, and the other is for
+//   other worlds.
+// - HTMLDocument's wrapper (window.document) in the context for the main
+//   world.
+//
+// Currently, the V8 context snapshot supports only the main thread. If it is
+// the main world, we need a special logic to serialize / deserialize
+// window.document (so only HTMLDocument is supported on the main world).
+// Worker threads are not yet supported.
+class CORE_EXPORT V8ContextSnapshot {
+  STATIC_ONLY(V8ContextSnapshot);
+
+ public:
+  static v8::Local<v8::Context> CreateContextFromSnapshot(
+      v8::Isolate*,
+      const DOMWrapperWorld&,
+      v8::ExtensionConfiguration*,
+      v8::Local<v8::Object> global_proxy,
+      Document*);
+  // Install runtime enabled features on some v8::Object's in a context
+  // created from a snapshot.
+  static void InstallRuntimeEnabledFeatures(v8::Local<v8::Context>, Document*);
+
+  static void EnsureInterfaceTemplates(v8::Isolate*);
+
+  static void SetReferenceTable(intptr_t* table);
+  static intptr_t* GetReferenceTable();
+
+  // Do not call this in production.
+  static v8::StartupData TakeSnapshot();
+
+ private:
+  static v8::StartupData SerializeInternalField(v8::Local<v8::Object> holder,
+                                                int index,
+                                                void* data);
+  static void DeserializeInternalField(v8::Local<v8::Object> holder,
+                                       int index,
+                                       v8::StartupData payload,
+                                       void* data);
+  static bool CanCreateContextFromSnapshot(v8::Isolate*,
+                                           const DOMWrapperWorld&,
+                                           Document*);
+
+  static void EnsureInterfaceTemplatesForWorld(v8::Isolate*,
+                                               const DOMWrapperWorld&);
+
+  static void TakeSnapshotForWorld(v8::SnapshotCreator*,
+                                   const DOMWrapperWorld&);
+};
+
+}  // namespace blink
+
+#endif  // V8ContextSnapshot_h