Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/app_list_button.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 "ash/shelf/app_list_button.h"
 
 #include <memory>
 #include <utility>
 
 #include "ash/public/cpp/shelf_types.h"
@@ skipping 26 matching lines @@
                              Shelf* shelf)
     : views::ImageButton(nullptr),
       is_showing_app_list_(false),
       background_color_(kShelfDefaultBaseColor),
       listener_(listener),
       shelf_view_(shelf_view),
       shelf_(shelf) {
   DCHECK(listener_);
   DCHECK(shelf_view_);
   DCHECK(shelf_);
-
+  Shell::Get()->AddShellObserver(this);
   SetInkDropMode(InkDropMode::ON_NO_GESTURE_HANDLER);
   set_ink_drop_base_color(kShelfInkDropBaseColor);
   set_ink_drop_visible_opacity(kShelfInkDropVisibleOpacity);
   SetAccessibleName(
       l10n_util::GetStringUTF16(IDS_ASH_SHELF_APP_LIST_LAUNCHER_TITLE));
   SetSize(gfx::Size(kShelfSize, kShelfSize));
   SetFocusPainter(TrayPopupUtils::CreateFocusPainter());
   set_notify_action(CustomButton::NOTIFY_ON_PRESS);
 }
 
-AppListButton::~AppListButton() {}
+AppListButton::~AppListButton() {
+  Shell::Get()->RemoveShellObserver(this);
+}
 
 void AppListButton::OnAppListShown() {
   AnimateInkDrop(views::InkDropState::ACTIVATED, nullptr);
   is_showing_app_list_ = true;
   shelf_->UpdateAutoHideState();
 }
 
 void AppListButton::OnAppListDismissed() {
   AnimateInkDrop(views::InkDropState::DEACTIVATED, nullptr);
   is_showing_app_list_ = false;
@@ skipping 163 matching lines @@
       alignment == SHELF_ALIGNMENT_BOTTOM_LOCKED) {
     return gfx::Point(x_mid, x_mid);
   } else if (alignment == SHELF_ALIGNMENT_RIGHT) {
     return gfx::Point(y_mid, y_mid);
   } else {
     DCHECK_EQ(alignment, SHELF_ALIGNMENT_LEFT);
     return gfx::Point(width() - y_mid, y_mid);
   }
 }
 
+void AppListButton::OnAppListShownOrDismissed(bool shown,
+                                              aura::Window* root_window) {
+  if (shown)
+    OnAppListShown();
+  else
+    OnAppListDismissed();

[xiyuan, 2017/06/06 15:51:04]

This is not right on multiple monitors. AppListButton is per shelf and shelf is
per display. So this would cause all AppListButton on all displays to change its
status, which is not right.

We need to filter it by root window.

[newcomer, 2017/06/06 16:42:29]

Done.

+}
+
 }  // namespace ash