Separate athena's startup process from AppShell's

athena/env/public/athena_env.h

+// Copyright 2014 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 ATHENA_ENV_PUBLIC_ATHENA_ENV_H_
+#define ATHENA_ENV_PUBLIC_ATHENA_ENV_H_
+
+#include "athena/athena_export.h"
+
+namespace gfx {
+class Insets;
+}
+
+namespace aura {
+class WindowTreeHost;
+}
+
+namespace athena {
+
+// AthenaEnv creates/shuts down the environment necessary to
+// start Athena shell.
+class ATHENA_EXPORT AthenaEnv {
+ public:
+  static void Create();
+  static AthenaEnv* Get();
+  static void Shutdown();
+
+  virtual ~AthenaEnv() {}
+
+  // Returns the single WindowTreeHost for the primary display.
+  virtual aura::WindowTreeHost* GetHost() = 0;
+
+  // Sets the insets for the primary displays's work area.
+  virtual void SetDisplayWorkAreaInsets(const gfx::Insets& insets) = 0;
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_ENV_PUBLIC_ATHENA_ENV_H_