[Device Service] Decouple NFC implementation from //content

content/browser/nfc/nfc_host.cc

+// 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 "content/browser/nfc/nfc_host.h"
+
+#include "base/atomic_sequence_num.h"
+#include "content/public/common/service_manager_connection.h"
+#include "device/nfc/nfc.mojom.h"
+#include "services/device/public/interfaces/constants.mojom.h"
+#include "services/service_manager/public/cpp/connector.h"
+
+#if defined(OS_ANDROID)
+#include "jni/NfcHost_jni.h"
+#endif
+
+namespace content {
+
+namespace {
+
+base::StaticAtomicSequenceNumber g_unique_id;
+
+}  // namespace
+
+NFCHost::NFCHost(WebContents* web_contents)
+    : id_(g_unique_id.GetNext()), web_contents_(web_contents) {
+  DCHECK(web_contents_);
+
+#if defined(OS_ANDROID)
+  JNIEnv* env = base::android::AttachCurrentThread();
+  java_nfc_host_.Reset(
+      Java_NfcHost_create(env, web_contents_->GetJavaWebContents().obj(), id_));
+
+  if (ServiceManagerConnection::GetForProcess()) {
+    service_manager::Connector* connector =
+        ServiceManagerConnection::GetForProcess()->GetConnector();
+    DCHECK(connector);

[jam, 2017/05/09 15:11:16]

nit: since the pointer is used in the next line, this DCHECK is gratuitous (i.e.
does nothing in release, and in debug the crash is as useful of a signal)

[blundell, 2017/05/10 13:15:25]

Done.

+    connector->BindInterface(device::mojom::kServiceName,
+                             mojo::MakeRequest(&nfc_provider_));
+  }
+#endif
+}
+
+void NFCHost::GetNFC(device::nfc::mojom::NFCRequest request) {
+#if defined(OS_ANDROID)
+  // Connect to an NFC object, associating it with |id_|.
+  nfc_provider_->GetNFCForHost(id_, std::move(request));

[dcheng, 2017/05/10 06:20:18]

Nit: #include <utility>

[blundell, 2017/05/10 13:15:25]

Done.

+#endif
+}
+
+NFCHost::~NFCHost() {}
+
+}  // namespace content