bindings: Define DictionaryBase class

Defines bindings::DictionaryBase as a base class for IDL dictionaries
generated by the new code generator.
This CL also prepares some basic APIs; NativeValueTraits and ToV8.


Bug: 839389
Change-Id: I47012911933c9bd6a8934f4d18f27e4a86e80974
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898893
Auto-Submit: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720902}

third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h

@@ -17,6 +17,10 @@ namespace blink {
 
 class CallbackFunctionBase;
 
+namespace bindings {
+class DictionaryBase;
+}  // namespace bindings
+
 // Boolean
 template <>
 struct CORE_EXPORT NativeValueTraits<IDLBoolean>
@@ -658,6 +662,20 @@ struct NativeValueTraits<IDLRecord<K, V>>
   }
 };
 
+// Dictionary
+template <typename T>
+struct NativeValueTraits<
+    T,
+    typename std::enable_if<
+        std::is_base_of<bindings::DictionaryBase, T>::value>::type>
+    : public NativeValueTraitsBase<T> {
+  static T* NativeValue(v8::Isolate* isolate,
+                        v8::Local<v8::Value> value,
+                        ExceptionState& exception_state) {
+    return T::Create(isolate, value, exception_state);
+  }
+};
+
 // Callback functions
 template <typename T>
 struct NativeValueTraits<

third_party/blink/renderer/platform/BUILD.gn

@@ -401,6 +401,7 @@ jumbo_component("platform") {
     "bindings/callback_method_retriever.cc",
     "bindings/callback_method_retriever.h",
     "bindings/custom_wrappable.h",
+    "bindings/dictionary_base.h",
     "bindings/dom_data_store.cc",
     "bindings/dom_data_store.h",
     "bindings/dom_wrapper_world.cc",

third_party/blink/renderer/platform/bindings/dictionary_base.h

+// Copyright 2019 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_BINDINGS_DICTIONARY_BASE_H_
+#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_BINDINGS_DICTIONARY_BASE_H_
+
+#include "third_party/blink/renderer/platform/heap/handle.h"
+#include "third_party/blink/renderer/platform/platform_export.h"
+#include "v8/include/v8.h"
+
+namespace blink {
+namespace bindings {
+
+// This class is the base class for all IDL dictionary implementations.  This is
+// designed to collaborate with NativeValueTraits and ToV8 with supporting type
+// dispatching (SFINAE, etc.).
+class PLATFORM_EXPORT DictionaryBase : public GarbageCollected<DictionaryBase> {
+ public:
+  virtual ~DictionaryBase() = default;
+
+  v8::Local<v8::Value> CreateV8Object(
+      v8::Isolate* isolate,
+      v8::Local<v8::Object> creation_context) const {
+    v8::Local<v8::Context> context = creation_context->CreationContext();
+    DCHECK(!context.IsEmpty());
+    v8::Local<v8::Object> v8_object;
+    {
+      v8::Context::Scope context_scope(context);
+      v8_object = v8::Object::New(isolate);
+    }
+    FillWithMembers(isolate, creation_context, v8_object);
+    return v8_object;
+  }
+
+ protected:
+  DictionaryBase() = default;
+
+  DictionaryBase(const DictionaryBase&) = delete;
+  DictionaryBase(const DictionaryBase&&) = delete;
+  DictionaryBase& operator=(const DictionaryBase&) = delete;
+  DictionaryBase& operator=(const DictionaryBase&&) = delete;
+
+  virtual void FillWithMembers(v8::Isolate* isolate,
+                               v8::Local<v8::Object> creation_context,
+                               v8::Local<v8::Object> v8_object) const = 0;
+};
+
+}  // namespace bindings
+}  // namespace blink
+
+#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_BINDINGS_DICTIONARY_BASE_H_

third_party/blink/renderer/platform/bindings/to_v8.h

@@ -15,6 +15,7 @@
 #include "base/time/time.h"
 #include "third_party/blink/renderer/platform/bindings/callback_function_base.h"
 #include "third_party/blink/renderer/platform/bindings/callback_interface_base.h"
+#include "third_party/blink/renderer/platform/bindings/dictionary_base.h"
 #include "third_party/blink/renderer/platform/bindings/dom_data_store.h"
 #include "third_party/blink/renderer/platform/bindings/script_state.h"
 #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
@@ -41,6 +42,19 @@ inline v8::Local<v8::Value> ToV8(ScriptWrappable* impl,
   return wrapper;
 }
 
+// Dictionary
+
+inline v8::Local<v8::Value> ToV8(bindings::DictionaryBase* dictionary,
+                                 v8::Local<v8::Object> creation_context,
+                                 v8::Isolate* isolate) {
+  if (UNLIKELY(!dictionary))
+    return v8::Null(isolate);
+  v8::Local<v8::Value> v8_value =
+      dictionary->CreateV8Object(isolate, creation_context);
+  DCHECK(!v8_value.IsEmpty());
+  return v8_value;
+}
+
 // Callback function
 
 inline v8::Local<v8::Value> ToV8(CallbackFunctionBase* callback,