Add helpers for creating UI components.

mojo/ui/view_provider_app.h

Index: mojo/ui/view_provider_app.h
diff --git a/mojo/ui/view_provider_app.h b/mojo/ui/view_provider_app.h
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+// 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 MOJO_UI_VIEW_PROVIDER_APP_H_
+#define MOJO_UI_VIEW_PROVIDER_APP_H_
+
+#include <string>
+
+#include "mojo/common/strong_binding_set.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_connection.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "mojo/public/cpp/system/core.h"
+#include "mojo/public/cpp/system/macros.h"
+#include "mojo/services/ui/views/interfaces/view_provider.mojom.h"
+
+namespace mojo {
+namespace ui {
+
+// Abstract implementation of a simple application that offers a ViewProvider.
+// Subclasses must provide a function to create the necessary Views.
+//
+// It is not necessary to use this class to implement all ViewProviders.
+// This class is merely intended to make the simple apps easier to write.
+class ViewProviderApp : public mojo::ApplicationDelegate,
+                        public mojo::InterfaceFactory<mojo::ui::ViewProvider> {
+ public:
+  ViewProviderApp();
+  ~ViewProviderApp() override;
+
+  mojo::ApplicationImpl* app_impl() { return app_impl_; }
+
+  // |ApplicationDelegate|:
+  void Initialize(mojo::ApplicationImpl* app) override;
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override;
+
+  // Called by the ViewProvider to create a view.
+  // This method may be called multiple times in the case where the
+  // view provider is asked to create multiple view instances.
+  //
+  // The |view_provider_url| is the connection URL of the view provider request.
+  //
+  // Returns true if successful, false if the view could not be created.
+  virtual bool CreateView(
+      const std::string& view_provider_url,
+      mojo::InterfaceRequest<mojo::ServiceProvider> services,
+      mojo::ServiceProviderPtr exposed_services,
+      const mojo::ui::ViewProvider::CreateViewCallback& callback) = 0;
+
+ private:
+  class DelegatingViewProvider;
+
+  // |InterfaceFactory<mojo::ui::ViewProvider>|:
+  void Create(mojo::ApplicationConnection* connection,
+              mojo::InterfaceRequest<mojo::ui::ViewProvider> request) override;
+
+  void CreateView(DelegatingViewProvider* provider,
+                  const std::string& view_provider_url,
+                  mojo::InterfaceRequest<mojo::ServiceProvider> services,
+                  mojo::ServiceProviderPtr exposed_services,
+                  const mojo::ui::ViewProvider::CreateViewCallback& callback);
+
+  mojo::ApplicationImpl* app_impl_ = nullptr;
+  mojo::StrongBindingSet<mojo::ui::ViewProvider> bindings_;
+
+  MOJO_DISALLOW_COPY_AND_ASSIGN(ViewProviderApp);
+};
+
+}  // namespace ui
+}  // namespace mojo
+
+#endif  // MOJO_UI_VIEW_PROVIDER_APP_H_