[Extensions] Harden against bindings interception

extensions/renderer/v8_helpers.h

 // Copyright 2015 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 EXTENSIONS_RENDERER_V8_HELPERS_H_
 #define EXTENSIONS_RENDERER_V8_HELPERS_H_
 
 #include <stdint.h>
 #include <string.h>
 
@@ skipping 42 matching lines @@
   return maybe.IsJust() && maybe.FromJust();
 }
 
 // Returns true if |value| is empty or undefined.
 inline bool IsEmptyOrUndefied(v8::Local<v8::Value> value) {
   return value.IsEmpty() || value->IsUndefined();
 }
 
 // SetProperty() family wraps V8::Object::DefineOwnProperty().
 // Returns true on success.
+// NOTE: Think about whether you want this or SetPrivateProperty() below.
+// TODO(devlin): Sort through more of the callers of this and see if we can
+// convert more to be private.
 inline bool SetProperty(v8::Local<v8::Context> context,
                         v8::Local<v8::Object> object,
                         v8::Local<v8::String> key,
                         v8::Local<v8::Value> value) {
   return IsTrue(object->DefineOwnProperty(context, key, value));
 }
 
 inline bool SetProperty(v8::Local<v8::Context> context,
                         v8::Local<v8::Object> object,
                         const char* key,
                         v8::Local<v8::Value> value) {
   v8::Local<v8::String> v8_key;
   if (!ToV8String(context->GetIsolate(), key, &v8_key))
     return false;
   return SetProperty(context, object, v8_key, value);
 }
 
 inline bool SetProperty(v8::Local<v8::Context> context,
                         v8::Local<v8::Object> object,
                         uint32_t index,
                         v8::Local<v8::Value> value) {
   return SetProperty(context, object, base::UintToString(index).c_str(), value);
 }
 
+// Wraps v8::Object::SetPrivate(). When possible, prefer this to SetProperty().
+inline bool SetPrivateProperty(v8::Local<v8::Context> context,
+                               v8::Local<v8::Object> object,
+                               v8::Local<v8::String> key,
+                               v8::Local<v8::Value> value) {
+  return IsTrue(object->SetPrivate(
+      context, v8::Private::ForApi(context->GetIsolate(), key), value));
+}
+
+inline bool SetPrivateProperty(v8::Local<v8::Context> context,
+                               v8::Local<v8::Object> object,
+                               const char* key,
+                               v8::Local<v8::Value> value) {
+  v8::Local<v8::String> v8_key;
+  return ToV8String(context->GetIsolate(), key, &v8_key) &&
+         IsTrue(object->SetPrivate(
+             context, v8::Private::ForApi(context->GetIsolate(), v8_key),
+             value));
+}
+
 // GetProperty() family calls V8::Object::Get() and extracts a value from
 // returned MaybeLocal. Returns true on success.
+// NOTE: Think about whether you want this or GetPrivateProperty() below.
 template <typename Key>
 inline bool GetProperty(v8::Local<v8::Context> context,
                         v8::Local<v8::Object> object,
                         Key key,
                         v8::Local<v8::Value>* out) {
   return object->Get(context, key).ToLocal(out);
 }
 
 inline bool GetProperty(v8::Local<v8::Context> context,
                         v8::Local<v8::Object> object,
                         const char* key,
                         v8::Local<v8::Value>* out) {
   v8::Local<v8::String> v8_key;
   if (!ToV8String(context->GetIsolate(), key, &v8_key))
     return false;
   return GetProperty(context, object, v8_key, out);
 }
 
+// Wraps v8::Object::GetPrivate(). When possible, prefer this to GetProperty().
+inline bool GetPrivateProperty(v8::Local<v8::Context> context,
+                               v8::Local<v8::Object> object,
+                               v8::Local<v8::String> key,
+                               v8::Local<v8::Value>* out) {
+  return object
+      ->GetPrivate(context, v8::Private::ForApi(context->GetIsolate(), key))
+      .ToLocal(out);
+}
+
+inline bool GetPrivateProperty(v8::Local<v8::Context> context,
+                               v8::Local<v8::Object> object,
+                               const char* key,
+                               v8::Local<v8::Value>* out) {
+  v8::Local<v8::String> v8_key;
+  return ToV8String(context->GetIsolate(), key, &v8_key) &&
+         GetPrivateProperty(context, object, v8_key, out);
+}
+
 // GetPropertyUnsafe() family wraps v8::Object::Get(). They crash when an
 // exception is thrown.
 inline v8::Local<v8::Value> GetPropertyUnsafe(v8::Local<v8::Context> context,
                                               v8::Local<v8::Object> object,
                                               v8::Local<v8::Value> key) {
   return object->Get(context, key).ToLocalChecked();
 }
 
 inline v8::Local<v8::Value> GetPropertyUnsafe(
     v8::Local<v8::Context> context,
@@ skipping 12 matching lines @@
                          int argc,
                          v8::Local<v8::Value> argv[],
                          v8::Local<v8::Value>* out) {
   return function->Call(context, recv, argc, argv).ToLocal(out);
 }
 
 }  // namespace v8_helpers
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_V8_HELPERS_H_