[Contextual Search] Add Mojo-enabled API component.

components/contextual_search/overlay_page_notifier_service_impl.h

+// Copyright 2015 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 COMPONENTS_CONTEXTUAL_SEARCH_OVERLAY_PAGE_NOTIFIER_SERVICE_IMPL_H_
+#define COMPONENTS_CONTEXTUAL_SEARCH_OVERLAY_PAGE_NOTIFIER_SERVICE_IMPL_H_
+
+#include "components/contextual_search/overlay_js_render_frame_observer.h"
+#include "components/contextual_search/overlay_page_notifier_service.mojom.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace contextual_search {
+
+class OverlayJsRenderFrameObserver;
+
+// OverlayPageNotifierService is responsible for listening to the browser for
+// messages about whether a page is presented in an overlay panel.
+// No message is received if the page is not presented in an overlay panel.
+// This service should be removed from the registry once the page is done
+// loading.
+class OverlayPageNotifierServiceImpl : public OverlayPageNotifierService {
+ public:
+  explicit OverlayPageNotifierServiceImpl(
+      OverlayJsRenderFrameObserver* observer,
+      mojo::InterfaceRequest<OverlayPageNotifierService> request);
+  ~OverlayPageNotifierServiceImpl() override;
+
+  // Implementation of mojo interface OverlayPageNotifierService.
+  void NotifyIsContextualSearchOverlay() override;
+
+ private:
+  mojo::StrongBinding<OverlayPageNotifierService> binding_;
+  OverlayJsRenderFrameObserver* overlay_js_observer_;
+};
+
+}  // namespace contextual_search
+
+#endif  // COMPONENTS_CONTEXTUAL_SEARCH_OVERLAY_PAGE_NOTIFIER_SERVICE_IMPL_H_