Draggable peeking/fullscreen launcher with transparent background.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index f4aa13a9d688aa1a1955cf3004a27b9164b5c23e..2c21b5bceefc88a93e8e3bb1896e75f8f9e0f57a 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -18,6 +18,7 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "ui/app_list/presenter/app_list_delegate.h"
 #include "ui/aura/window.h"
 #include "ui/display/screen.h"
 #include "ui/events/event_target.h"
@@ -91,7 +92,6 @@ namespace ash {
 
 class AcceleratorController;
 class AccessibilityDelegate;
-class AppListDelegateImpl;
 class AshNativeCursorManager;
 class AshTouchTransformController;
 class AutoclickController;
@@ -193,7 +193,8 @@ class SmsObserverTest;
 class ASH_EXPORT Shell : public SessionObserver,
                          public SystemModalContainerEventFilterDelegate,
                          public ui::EventTarget,
-                         public ::wm::ActivationChangeObserver {
+                         public ::wm::ActivationChangeObserver,
+                         public app_list::AppListDelegate {
  public:
   typedef std::vector<RootWindowController*> RootWindowControllerList;
 
@@ -559,6 +560,9 @@ class ASH_EXPORT Shell : public SessionObserver,
   // TODO(oshima): Investigate if we can merge this and |OnLoginStateChanged|.
   void UpdateAfterLoginStatusChange(LoginStatus status);
 
+  // Notifies observers that the AppList has been shown or dismissed.
+  void NotifyAppListVisibilityChanged(bool shown, aura::Window* root_window);

[sky, 2017/06/07 20:21:36]

The reason there are various NotifyFoo functions here is so other classes can
call them. That isn't the case with applist. So, move the implementation of
NotifyApplistVisibilityChanged to OnAppListVisibilityChanged and remove
NotifyApplistVisibilityChanged.

[newcomer, 2017/06/08 21:59:05]

Done.

+
   // Notifies observers that maximize mode has started, windows might still
   // animate.
   void NotifyMaximizeModeStarted();
@@ -647,6 +651,9 @@ class ASH_EXPORT Shell : public SessionObserver,
                          aura::Window* gained_active,
                          aura::Window* lost_active) override;
 
+  // Overridden from app_list::AppListDelegate:
+  void OnAppListVisibilityChanged(bool visible, int64_t display_id_) override;
+
   // SessionObserver:
   void OnSessionStateChanged(session_manager::SessionState state) override;
   void OnLoginStatusChanged(LoginStatus login_status) override;
@@ -821,8 +828,6 @@ class ASH_EXPORT Shell : public SessionObserver,
 
   std::unique_ptr<ImmersiveHandlerFactoryAsh> immersive_handler_factory_;
 
-  std::unique_ptr<AppListDelegateImpl> app_list_delegate_impl_;
-
   base::ObserverList<ShellObserver> shell_observers_;
 
   scoped_refptr<base::SequencedWorkerPool> blocking_pool_;