[Chromecast] Add support for z-order and window focus.

chromecast/graphics/cast_window_manager_aura.h

 // Copyright 2017 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 CHROMECAST_GRAPHICS_CAST_WINDOW_MANAGER_AURA_H_
 #define CHROMECAST_GRAPHICS_CAST_WINDOW_MANAGER_AURA_H_
 
 #include <memory>
+#include <vector>
 
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "chromecast/graphics/cast_vsync_settings.h"
 #include "chromecast/graphics/cast_window_manager.h"
+#include "ui/aura/client/focus_client.h"
+#include "ui/aura/window_observer.h"
 
 namespace aura {
 class Window;
 namespace client {
 class DefaultCaptureClient;
 }  // namespace client
 }  // namespace aura
 
 namespace chromecast {
 
 class CastWindowTreeHost;
 
 class CastWindowManagerAura : public CastWindowManager,
-                              private CastVSyncSettings::Observer {
+                              private CastVSyncSettings::Observer,
+                              private aura::WindowObserver,
+                              private aura::client::FocusClient {
  public:
   ~CastWindowManagerAura() override;
 
   // CastWindowManager implementation:
   void TearDown() override;
   void AddWindow(gfx::NativeView window) override;
 
+  // aura::client::FocusClient implementation:
+  void AddObserver(aura::client::FocusChangeObserver* observer) override;
+  void RemoveObserver(aura::client::FocusChangeObserver* observer) override;
+  void FocusWindow(aura::Window* window) override;
+  void ResetFocusWithinActiveWindow(aura::Window* window) override;
+  aura::Window* GetFocusedWindow() override;
+
  private:
   friend class CastWindowManager;
 
   // This class should only be instantiated by CastWindowManager::Create.
   explicit CastWindowManagerAura(bool enable_input);
 
   // CastVSyncSettings::Observer implementation:
   void OnVSyncIntervalChanged(base::TimeDelta interval) override;
 
+  // aura::WindowObserver implementation:
+  void OnWindowVisibilityChanged(aura::Window* window, bool visible) override;
+  void OnWindowDestroying(aura::Window* window) override;
+  void OnWindowHierarchyChanging(const HierarchyChangeParams& params) override;
+
   void Setup();
 
   const bool enable_input_;
   std::unique_ptr<CastWindowTreeHost> window_tree_host_;
+  base::ObserverList<aura::client::FocusChangeObserver> focus_observers_;
   std::unique_ptr<aura::client::DefaultCaptureClient> capture_client_;
 
+  // Track the currently focused window, which isn't necessarily a top-level
+  // window.
+  aura::Window* focused_window_;
+  // Track the windows that we've focused in the past, so that we can restore
+  // focus to them.  We assume that this is a small list so that we can perform
+  // linear ops on it.
+  std::vector<aura::Window*> focusable_windows_;
+
+  // Change the focused window and notify focus observers.
+  void UpdateWindowFocus(aura::Window* skip);
+  // Get the window that should be focused.
+  aura::Window* GetWindowToFocus(aura::Window* skip);
+
+  // Return the top-level window for |window|.
+  aura::Window* GetTopLevelWindow(aura::Window* window);
+
   DISALLOW_COPY_AND_ASSIGN(CastWindowManagerAura);
 };
 
 }  // namespace chromecast
 
 #endif  // CHROMECAST_GRAPHICS_CAST_WINDOW_MANAGER_AURA_H_