feat: [extensions] background pages (#21591)

shell/browser/extensions/electron_extensions_api_client.cc

@@ -0,0 +1,29 @@
+// Copyright (c) 2019 Slack Technologies, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "shell/browser/extensions/electron_extensions_api_client.h"
+
+#include <memory>
+
+#include "shell/browser/extensions/atom_extension_web_contents_observer.h"
+#include "shell/browser/extensions/electron_messaging_delegate.h"
+
+namespace extensions {
+
+ElectronExtensionsAPIClient::ElectronExtensionsAPIClient() = default;
+ElectronExtensionsAPIClient::~ElectronExtensionsAPIClient() = default;
+
+MessagingDelegate* ElectronExtensionsAPIClient::GetMessagingDelegate() {
+  if (!messaging_delegate_)
+    messaging_delegate_ = std::make_unique<ElectronMessagingDelegate>();
+  return messaging_delegate_.get();
+}
+
+void ElectronExtensionsAPIClient::AttachWebContentsHelpers(
+    content::WebContents* web_contents) const {
+  extensions::AtomExtensionWebContentsObserver::CreateForWebContents(
+      web_contents);
+}
+
+}  // namespace extensions