ash: Remove ash::Shelf in favor of ash::WmShelf

ash/mus/bridge/wm_shelf_mus.cc

Index: ash/mus/bridge/wm_shelf_mus.cc
diff --git a/ash/mus/bridge/wm_shelf_mus.cc b/ash/mus/bridge/wm_shelf_mus.cc
index 951ee63f196efa2978ceef27e5e05adf8ef9e1e1..0b03fcff97c8928fc6b9974b89897563e042dc48 100644
--- a/ash/mus/bridge/wm_shelf_mus.cc
+++ b/ash/mus/bridge/wm_shelf_mus.cc
@@ -4,8 +4,6 @@
 
 #include "ash/mus/bridge/wm_shelf_mus.h"
 
-#include "ash/common/shelf/shelf.h"
-#include "ash/common/shelf/shelf_delegate.h"
 #include "ash/common/shelf/shelf_widget.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/wm_root_window_controller.h"
@@ -22,20 +20,14 @@ WmShelfMus::WmShelfMus(WmRootWindowController* root_window_controller) {
   shelf_widget_.reset(new ShelfWidget(
       root->GetChildByShellWindowId(kShellWindowId_ShelfContainer),
       root->GetChildByShellWindowId(kShellWindowId_StatusContainer), this));
-  shelf_.reset(
-      new Shelf(this, shelf_widget_->CreateShelfView(), shelf_widget_.get()));
-  shelf_widget_->set_shelf(shelf_.get());
-  // Must be initialized before the delegate is notified because the delegate
-  // may try to access the WmShelf.
-  SetShelf(shelf_.get());
-  WmShell::Get()->shelf_delegate()->OnShelfCreated(this);
+  InitializeShelf();
   WmShell::Get()->NotifyShelfCreatedForRootWindow(root);
   shelf_widget_->PostCreateShelf();
 }
 
 WmShelfMus::~WmShelfMus() {
   shelf_widget_.reset();
-  WmShelf::ClearShelf();
+  ShutdownShelf();
 }
 
 void WmShelfMus::WillDeleteShelfLayoutManager() {