[gin] Allow interceptors to signal whether a they intercepted something

gin/interceptor.cc

 // Copyright 2014 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 "gin/interceptor.h"
 
 #include <map>
 
 #include "gin/per_isolate_data.h"
 
 namespace gin {
 
 NamedPropertyInterceptor::NamedPropertyInterceptor(v8::Isolate* isolate,
                                                    WrappableBase* base)
     : isolate_(isolate), base_(base) {
   PerIsolateData::From(isolate_)->SetNamedPropertyInterceptor(base_, this);
 }
 
 NamedPropertyInterceptor::~NamedPropertyInterceptor() {
   PerIsolateData::From(isolate_)->ClearNamedPropertyInterceptor(base_, this);
 }
 
 v8::Local<v8::Value> NamedPropertyInterceptor::GetNamedProperty(
     v8::Isolate* isolate,
     const std::string& property) {
   return v8::Local<v8::Value>();
 }
 
-void NamedPropertyInterceptor::SetNamedProperty(v8::Isolate* isolate,
+bool NamedPropertyInterceptor::SetNamedProperty(v8::Isolate* isolate,
                                                 const std::string& property,
-                                                v8::Local<v8::Value> value) {}
+                                                v8::Local<v8::Value> value) {
+  return false;
+}
 
 std::vector<std::string> NamedPropertyInterceptor::EnumerateNamedProperties(
     v8::Isolate* isolate) {
   return std::vector<std::string>();
 }
 
 IndexedPropertyInterceptor::IndexedPropertyInterceptor(v8::Isolate* isolate,
                                                        WrappableBase* base)
     : isolate_(isolate), base_(base) {
   PerIsolateData::From(isolate_)->SetIndexedPropertyInterceptor(base_, this);
 }
 
 IndexedPropertyInterceptor::~IndexedPropertyInterceptor() {
   PerIsolateData::From(isolate_)->ClearIndexedPropertyInterceptor(base_, this);
 }
 
 v8::Local<v8::Value> IndexedPropertyInterceptor::GetIndexedProperty(
     v8::Isolate* isolate,
     uint32_t index) {
   return v8::Local<v8::Value>();
 }
 
-void IndexedPropertyInterceptor::SetIndexedProperty(
+bool IndexedPropertyInterceptor::SetIndexedProperty(
     v8::Isolate* isolate,
     uint32_t index,
-    v8::Local<v8::Value> value) {}
+    v8::Local<v8::Value> value) {
+  return false;
+}
 
 std::vector<uint32_t> IndexedPropertyInterceptor::EnumerateIndexedProperties(
     v8::Isolate* isolate) {
   return std::vector<uint32_t>();
 }
 
 }  // namespace gin