athena: Add the concept of Activity and related managers.

athena/main/sample_activity.cc

+// 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.
+
+#include "athena/main/sample_activity.h"
+
+#include "ui/aura/window.h"
+
+SampleActivity::SampleActivity(SkColor color,
+                               SkColor content_color,
+                               const std::string& title)
+    : color_(color), content_color_(content_color), title_(title) {
+}
+
+SampleActivity::~SampleActivity() {
+}
+
+athena::ActivityViewModel* SampleActivity::GetActivityViewModel() {
+  return this;
+}
+
+SkColor SampleActivity::GetRepresentativeColor() {
+  return color_;
+}
+
+std::string SampleActivity::GetTitle() {
+  return title_;
+}
+
+aura::Window* SampleActivity::GetNativeWindow() {
+  if (!window_) {
+    window_.reset(new aura::Window(NULL));
+    window_->Init(aura::WINDOW_LAYER_SOLID_COLOR);
+    window_->layer()->SetColor(content_color_);
+  }
+  return window_.get();
+}