chrome/browser/ui/aura/active_desktop_monitor.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_UI_AURA_ACTIVE_DESKTOP_MONITOR_H_
   6 #define CHROME_BROWSER_UI_AURA_ACTIVE_DESKTOP_MONITOR_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/compiler_specific.h"
  10 #include "chrome/browser/ui/host_desktop.h"
  11 #include "ui/aura/env_observer.h"
  12
  13 // Tracks the most-recently activated host desktop type by observing
  14 // WindowTreeHost activations.
  15 class ActiveDesktopMonitor : public aura::EnvObserver {
  16  public:
  17   // Constructs an ActiveDesktopMonitor which initially uses |initial_desktop|
  18   // as the |last_activated_desktop_| until a root window is activated.
  19   explicit ActiveDesktopMonitor(chrome::HostDesktopType initial_desktop);
  20   ~ActiveDesktopMonitor() override;
  21
  22   // Returns the host desktop type of the most-recently activated
  23   // WindowTreeHost. This desktop type may no longer exist (e.g., the Ash
  24   // desktop may have closed since being active, and no RWHs on the native
  25   // desktop have yet been activated).
  26   static chrome::HostDesktopType GetLastActivatedDesktopType();
  27
  28  private:
  29   // Returns true if |host| is a DesktopWindowTreeHost.
  30   static bool IsDesktopWindow(aura::WindowTreeHost* host);
  31
  32   // aura::EnvObserver methods.
  33   void OnWindowInitialized(aura::Window* window) override;
  34   void OnHostActivated(aura::WindowTreeHost* host) override;
  35
  36   static ActiveDesktopMonitor* g_instance_;
  37   chrome::HostDesktopType last_activated_desktop_;
  38
  39   DISALLOW_COPY_AND_ASSIGN(ActiveDesktopMonitor);
  40 };
  41
  42 #endif  // CHROME_BROWSER_UI_AURA_ACTIVE_DESKTOP_MONITOR_H_