athena: Add the concept of Activity and related managers.

athena/activity/public/activity_view_model.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_ACTIVITY_PUBLIC_ACTIVITY_VIEW_MODEL_H_
+#define ATHENA_ACTIVITY_PUBLIC_ACTIVITY_VIEW_MODEL_H_
+
+#include <string>
+
+#include "athena/athena_export.h"
+
+typedef unsigned int SkColor;
+
+namespace aura {
+class Window;
+}
+
+namespace athena {
+
+class ATHENA_EXPORT ActivityViewModel {
+ public:
+  virtual ~ActivityViewModel() {}
+
+  // Returns a color most representative of this activity.
+  virtual SkColor GetRepresentativeColor() = 0;
+
+  // Returns a title for the activity.
+  virtual std::string GetTitle() = 0;
+
+  // Returns the native window containing the activity.
+  virtual aura::Window* GetNativeWindow() = 0;
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_ACTIVITY_PUBLIC_ACTIVITY_VIEW_MODEL_H_