Adding field to tell if gin::IsolateHolder needs lock to be accessed.

gin/public/isolate_holder.h

 // Copyright 2013 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 GIN_PUBLIC_ISOLATE_HOLDER_H_
 #define GIN_PUBLIC_ISOLATE_HOLDER_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "gin/gin_export.h"
 #include "v8/include/v8.h"
 
 namespace gin {
 
 class PerIsolateData;
 class RunMicrotasksObserver;
 
 // To embed Gin, first initialize gin using IsolateHolder::Initialize and then
 // create an instance of IsolateHolder to hold the v8::Isolate in which you
 // will execute JavaScript. You might wish to subclass IsolateHolder if you
 // want to tie more state to the lifetime of the isolate.
 class GIN_EXPORT IsolateHolder {
  public:
   // Controls whether or not V8 should only accept strict mode scripts.
   enum ScriptMode {
     kNonStrictMode,
     kStrictMode
   };
 
+  // Stores whether the client uses v8::Locker to access the isolate.
+  enum AccessMode {
+    kSingleThread,
+    kUseLocker
+  };
+
   IsolateHolder();
+  explicit IsolateHolder(AccessMode access_mode);
   ~IsolateHolder();
 
   // Should be invoked once before creating IsolateHolder instances to
   // initialize V8 and Gin. In case V8_USE_EXTERNAL_STARTUP_DATA is
   // defined, V8's initial snapshot should be loaded (by calling
   // V8Initializer::LoadV8SnapshotFromFD or
   // V8Initializer::LoadV8Snapshot) before calling this method.
   static void Initialize(ScriptMode mode,
                          v8::ArrayBuffer::Allocator* allocator);
 
   v8::Isolate* isolate() { return isolate_; }
 
   // The implementations of Object.observe() and Promise enqueue v8 Microtasks
   // that should be executed just before control is returned to the message
   // loop. This method adds a MessageLoop TaskObserver which runs any pending
   // Microtasks each time a Task is completed. This method should be called
   // once, when a MessageLoop is created and it should be called on the
   // MessageLoop's thread.
   void AddRunMicrotasksObserver();
 
   // This method should also only be called once, and on the MessageLoop's
   // thread.
   void RemoveRunMicrotasksObserver();
 
+  // This method returns if v8::Locker is needed to access isolate.
+  AccessMode access_mode() const { return access_mode_; }
+
  private:
   v8::Isolate* isolate_;
   scoped_ptr<PerIsolateData> isolate_data_;
   scoped_ptr<RunMicrotasksObserver> task_observer_;
+  AccessMode access_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolateHolder);
 };
 
 }  // namespace gin
 
 #endif  // GIN_PUBLIC_ISOLATE_HOLDER_H_