Draggable peeking/fullscreen launcher with transparent background.

ash/app_list/app_list_delegate_impl.cc

 // 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.
 
 #include "ash/app_list/app_list_delegate_impl.h"
 
 #include "ash/root_window_controller.h"
 #include "ash/shelf/app_list_button.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_widget.h"
 #include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/wm_window.h"
+#include "ui/app_list/app_list_features.h"
 #include "ui/app_list/presenter/app_list.h"
 
 namespace ash {
 
 AppListDelegateImpl::AppListDelegateImpl() {
   Shell::Get()->app_list()->set_delegate(this);
 }
 
 AppListDelegateImpl::~AppListDelegateImpl() {
   Shell::Get()->app_list()->set_delegate(nullptr);
 }
 
 void AppListDelegateImpl::OnAppListVisibilityChanged(bool visible,
                                                      int64_t display_id) {
   aura::Window* root_window =
       ShellPort::Get()->GetRootWindowForDisplayId(display_id);
   AppListButton* app_list_button =
       Shelf::ForWindow(root_window)->shelf_widget()->GetAppListButton();
   if (!app_list_button)
     return;
 
   if (visible)
     app_list_button->OnAppListShown();
   else
     app_list_button->OnAppListDismissed();
+
+  if (app_list::features::IsFullscreenAppListEnabled()) {
+    Shelf* shelf = Shelf::ForWindow(root_window);
+    shelf->OnAppListIsActive(visible);

[xiyuan, 2017/05/30 22:18:50]

nit: get rid of |shelf| and use Shelf::ForWindow in-place

i.e.
  Shelf::ForWindow(root_window)->OnAppListIsActive(visible);

and if it could fit in one line, get rid of {} as well.

[newcomer, 2017/06/01 01:42:53]

Done.

[sky, 2017/06/01 13:34:05]

Thanks for starting down this path! What I'm really suggesting here is Shell
becomes the ApplistDelegate. Shell::OnApplistVisibilityChanged() *always* calls
to OnAppListIsActive, or at this point we should name it
OnAppListVisibilityChanged(). Shelf code has a ShellObserver that updates both
the app-list_button and whatever you need the new code to do? In other words,
I'm suggesting you nuke this class entirely.

[newcomer, 2017/06/05 22:01:44]

Discussed Offline, I've created a bug and plan merge the change into a new CL.

+  }
 }
 
 }  // namespace ash