ash: Explicitly teach various components about ShelfLayoutManager.

ash/system/web_notification/ash_popup_alignment_delegate.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/system/web_notification/ash_popup_alignment_delegate.h"
 
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf_constants.h"
 #include "ash/shelf/shelf_layout_manager.h"
@@ skipping 14 matching lines @@
 
 const int kToastMarginX = 3;
 
 // If there should be no margin for the first item, this value needs to be
 // substracted to flush the message to the shelf (the width of the border +
 // shadow).
 const int kNoToastMarginBorderAndShadowOffset = 2;
 
 }
 
-AshPopupAlignmentDelegate::AshPopupAlignmentDelegate()
-    : screen_(NULL), root_window_(NULL), shelf_(NULL), system_tray_height_(0) {
+AshPopupAlignmentDelegate::AshPopupAlignmentDelegate(ShelfLayoutManager* shelf)
+    : screen_(NULL), root_window_(NULL), shelf_(shelf), system_tray_height_(0) {
+  shelf_->AddObserver(this);
 }
 
 AshPopupAlignmentDelegate::~AshPopupAlignmentDelegate() {
   if (screen_)
     screen_->RemoveObserver(this);
   Shell::GetInstance()->RemoveShellObserver(this);
-  if (shelf_)
-    shelf_->RemoveObserver(this);
+  shelf_->RemoveObserver(this);
 }
 
 void AshPopupAlignmentDelegate::StartObserving(gfx::Screen* screen,
                                                const gfx::Display& display) {
   screen_ = screen;
   work_area_ = display.work_area();
   root_window_ = ash::Shell::GetInstance()
                      ->window_tree_host_manager()
                      ->GetRootWindowForDisplayId(display.id());
-  UpdateShelf();
   screen->AddObserver(this);
   Shell::GetInstance()->AddShellObserver(this);
   if (system_tray_height_ > 0)
     UpdateWorkArea();
 }
 
 void AshPopupAlignmentDelegate::SetSystemTrayHeight(int height) {
   system_tray_height_ = height;
 
   // If the shelf is shown during auto-hide state, the distance from the edge
   // should be reduced by the height of shelf's shown height.
-  if (shelf_ && shelf_->visibility_state() == SHELF_AUTO_HIDE &&
+  if (shelf_->visibility_state() == SHELF_AUTO_HIDE &&
       shelf_->auto_hide_state() == SHELF_AUTO_HIDE_SHOWN) {
     system_tray_height_ -= kShelfSize - ShelfLayoutManager::kAutoHideSize;
   }
 
   if (system_tray_height_ > 0)
     system_tray_height_ += message_center::kMarginBetweenItems;
   else
     system_tray_height_ = 0;
 
-  if (!shelf_)
-    return;
-
   DoUpdateIfPossible();
 }
 
 int AshPopupAlignmentDelegate::GetToastOriginX(
     const gfx::Rect& toast_bounds) const {
   // In Ash, RTL UI language mirrors the whole ash layout, so the toast
   // widgets should be at the bottom-left instead of bottom right.
   if (base::i18n::IsRTL())
     return work_area_.x() + kToastMarginX;
 
@@ skipping 21 matching lines @@
 bool AshPopupAlignmentDelegate::IsFromLeft() const {
   return GetAlignment() == SHELF_ALIGNMENT_LEFT;
 }
 
 void AshPopupAlignmentDelegate::RecomputeAlignment(
     const gfx::Display& display) {
   // Nothing needs to be done.
 }
 
 ShelfAlignment AshPopupAlignmentDelegate::GetAlignment() const {
-  return shelf_ ? shelf_->GetAlignment() : SHELF_ALIGNMENT_BOTTOM;
-}
-
-void AshPopupAlignmentDelegate::UpdateShelf() {
-  if (shelf_)
-    return;
-
-  shelf_ = ShelfLayoutManager::ForShelf(root_window_);
-  if (shelf_)
-    shelf_->AddObserver(this);
+  return shelf_->GetAlignment();
 }
 
 gfx::Display AshPopupAlignmentDelegate::GetCurrentDisplay() const {
   return gfx::Screen::GetScreen()->GetDisplayNearestWindow(
       shelf_->shelf_widget()->GetNativeView());
 }
 
 void AshPopupAlignmentDelegate::UpdateWorkArea() {
   work_area_ = shelf_->user_work_area_bounds();
   DoUpdateIfPossible();
 }
 
 void AshPopupAlignmentDelegate::OnDisplayWorkAreaInsetsChanged() {
-  UpdateShelf();
   UpdateWorkArea();
 }
 
 void AshPopupAlignmentDelegate::WillChangeVisibilityState(
     ShelfVisibilityState new_state) {
   UpdateWorkArea();
 }
 
 void AshPopupAlignmentDelegate::OnAutoHideStateChanged(
     ShelfAutoHideState new_state) {
   UpdateWorkArea();
 }
 
 void AshPopupAlignmentDelegate::OnDisplayAdded(
     const gfx::Display& new_display) {
 }
 
 void AshPopupAlignmentDelegate::OnDisplayRemoved(
     const gfx::Display& old_display) {
 }
 
 void AshPopupAlignmentDelegate::OnDisplayMetricsChanged(
     const gfx::Display& display,
     uint32_t metrics) {
-  UpdateShelf();
-  if (shelf_ && GetCurrentDisplay().id() == display.id())
+  if (GetCurrentDisplay().id() == display.id())
     UpdateWorkArea();
 }
 
 }  // namespace ash