Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/shelf_layout_manager.cc

Index: ash/shelf/shelf_layout_manager.cc
diff --git a/ash/shelf/shelf_layout_manager.cc b/ash/shelf/shelf_layout_manager.cc
index 229e4c24e3690c381f0e5473b2278947c21f21ad..cbe502f3232efaee2395e3dcc39db3e97d55058b 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -28,6 +28,7 @@
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/i18n/rtl.h"
+#include "ui/app_list/app_list_features.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_observer.h"
@@ -173,6 +174,10 @@ ShelfLayoutManager::~ShelfLayoutManager() {
   ShellPort::Get()->RemoveLockStateObserver(this);
 }
 
+void ShelfLayoutManager::OnAppListIsActive() {
+  MaybeUpdateShelfBackground(AnimationChangeType::IMMEDIATE);
+}
+
 void ShelfLayoutManager::PrepareForShutdown() {
   in_shutdown_ = true;
   // Stop observing changes to avoid updating a partially destructed shelf.
@@ -425,6 +430,15 @@ void ShelfLayoutManager::OnVirtualKeyboardStateChanged(
       &keyboard_observer_);
 }
 
+void ShelfLayoutManager::OnAppListShownOrDismissed(bool shown,
+                                                   aura::Window* root_window) {
+  if (shelf_widget() == Shelf::ForWindow(root_window)->shelf_widget()) {
+    app_list_is_being_shown = shown;
+    if (app_list::features::IsFullscreenAppListEnabled())
+      MaybeUpdateShelfBackground(AnimationChangeType::IMMEDIATE);
+  }
+}
+
 void ShelfLayoutManager::OnWindowActivated(ActivationReason reason,
                                            aura::Window* gained_active,
                                            aura::Window* lost_active) {
@@ -468,6 +482,11 @@ ShelfBackgroundType ShelfLayoutManager::GetShelfBackgroundType() const {
   if (state_.session_state != session_manager::SessionState::ACTIVE)
     return SHELF_BACKGROUND_OVERLAP;
 
+  // If the app list is active, hide the shelf background to prevent overlap.
+  if (app_list_is_being_shown &&
+      app_list::features::IsFullscreenAppListEnabled())
+    return SHELF_BACKGROUND_DEFAULT;
+
   if (state_.visibility_state != SHELF_AUTO_HIDE &&
       state_.window_state == wm::WORKSPACE_WINDOW_STATE_MAXIMIZED) {
     return SHELF_BACKGROUND_MAXIMIZED;