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::OnAppListVisibilityChanged(bool shown,
+                                               aura::Window* root_window) {
+  if (shelf_ != Shelf::ForWindow(root_window))
+    return;
+
+  if (shown)
+    OnAppListShown();
+  else
+    OnAppListDismissed();
+}
+
 }  // namespace ash