Split Screen mode implementation

athena/wm/mru_window_tracker.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/wm/mru_window_tracker.h"
+
+#include "ui/aura/window.h"
+
+namespace athena {
+
+MruWindowTracker::MruWindowTracker(aura::Window* container)
+    : container_(container) {
+  container->AddObserver(this);
+}
+
+MruWindowTracker::~MruWindowTracker() {
+  if (container_)
+    container_->RemoveObserver(this);
+}
+
+aura::Window::Windows MruWindowTracker::GetWindowList() const {
+  return aura::Window::Windows(mru_windows_.begin(), mru_windows_.end());
+}
+
+void MruWindowTracker::MoveToFront(aura::Window* window) {
+  DCHECK(window);
+  CHECK_EQ(container_, window->parent());
+  std::list<aura::Window*>::iterator it =
+      std::find(mru_windows_.begin(), mru_windows_.end(), window);
+  DCHECK(it != mru_windows_.end());
+  mru_windows_.erase(it);
+  mru_windows_.push_back(window);
+}
+
+// Overridden from WindowObserver:
+void MruWindowTracker::OnWillRemoveWindow(aura::Window* window) {
+  std::list<aura::Window*>::iterator it =
+      std::find(mru_windows_.begin(), mru_windows_.end(), window);
+  if (it == mru_windows_.end()) {
+    // All normal windows should be tracked in mru_windows_
+    DCHECK_NE(window->type(), ui::wm::WINDOW_TYPE_NORMAL);
+    return;
+  }
+  mru_windows_.erase(it);
+}
+
+void MruWindowTracker::OnWindowAdded(aura::Window* new_window) {
+  // We are only interested in ordering normal windows.
+  if (new_window->type() == ui::wm::WINDOW_TYPE_NORMAL)
+    mru_windows_.push_back(new_window);
+}
+
+}  // namespace athena