Initial stub version of Async Clipboard API

third_party/WebKit/Source/core/frame/NavigatorClipboard.cpp

+// 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.
+
+#include "core/frame/NavigatorClipboard.h"
+
+#include "core/clipboard/Clipboard.h"
+#include "core/dom/Document.h"
+#include "core/frame/LocalFrame.h"
+
+namespace blink {
+
+Clipboard* NavigatorClipboard::clipboard(ScriptState* scriptState,
+                                         Navigator& navigator) {
+  NavigatorClipboard* supplement = static_cast<NavigatorClipboard*>(
+      Supplement<Navigator>::From(navigator, SupplementName()));
+  if (!supplement) {
+    supplement = new NavigatorClipboard(navigator);
+    ProvideTo(navigator, SupplementName(), supplement);
+  }
+
+  if (!supplement->m_clipboard) {

[dcheng, 2017/06/06 23:33:38]

Nit: let's just have NavigatorClipboard construct it internally rather than
creating it on demand here.

[garykac, 2017/06/09 20:38:59]

Done.

+    supplement->m_clipboard = new Clipboard(
+        supplement->GetSupplementable()->GetFrame()
+            ? supplement->GetSupplementable()->GetFrame()->GetDocument()
+            : nullptr);
+  }
+
+  return supplement->m_clipboard;
+}
+
+DEFINE_TRACE(NavigatorClipboard) {
+  visitor->Trace(m_clipboard);
+  Supplement<Navigator>::Trace(visitor);
+}
+
+NavigatorClipboard::NavigatorClipboard(Navigator& navigator)
+    : Supplement<Navigator>(navigator) {}
+
+const char* NavigatorClipboard::SupplementName() {
+  return "NavigatorClipboard";
+}
+
+}  // namespace blink