Add mojo service for CopylessPaste in Blink

third_party/WebKit/Source/modules/document_metadata/CopylessPasteServer.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 "modules/document_metadata/CopylessPasteServer.h"
+
+#include "core/frame/LocalFrame.h"
+#include "modules/document_metadata/CopylessPasteExtractor.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace blink {
+
+CopylessPasteServer::CopylessPasteServer(LocalFrame& frame) : m_frame(frame) {}
+
+void CopylessPasteServer::bindMojoRequest(
+    LocalFrame* frame,
+    mojom::blink::CopylessPasteRequest request) {
+  DCHECK(frame);
+
+  mojo::MakeStrongBinding(WTF::wrapUnique(new CopylessPasteServer(*frame)),

[dcheng, 2017/03/30 21:21:00]

Nit: WTF::makeUnique?

[wychen, 2017/03/31 07:51:54]

Done.

+                          std::move(request));
+}
+
+void CopylessPasteServer::GetEntities(const GetEntitiesCallback& callback) {

[dcheng, 2017/03/30 21:21:00]

What's the expected lifetime of this service? Is it supposed to persist between
navigations?

(Most Mojo things in Blink subclass ContextLifecycleObserver and close the
binding on contextDestroyed() -- should we be doing that here?)

[wychen, 2017/03/30 21:33:28]

This service is stateless. When getting a request (happens at onLoad), it would
scan the DOM and return some metadata. I think it should work either way.

[wychen, 2017/04/05 19:25:50]

Most of the Mojo things in Blink are Mojo clients, not Mojo servers. Mojo
clients for JavaScript should terminate when the context is gone.

In this case, it's a Mojo server, so I think it is not necessary for it to
self-destruct when the context is gone.

+  if (!m_frame || !m_frame->document()) {
+    callback.Run(mojom::blink::WebPage::New());
+    return;
+  }
+  mojom::blink::WebPagePtr webpage = mojom::blink::WebPage::New();
+  // TODO(wychen): connect with CopylessPasteExtractor::extract() like:
+  // CopylessPasteExtractor::extract(*m_frame->document(), webpage);
+  callback.Run(std::move(webpage));
+}
+
+}  // namespace blink