Moves maintaining ShellObservers back to Shell

chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc

Index: chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
diff --git a/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc b/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
index 8f383f9ce204e3d76ee2876cdf529f99a532a523..c625c9fdfe9303e5389678a27462bec5e4d34d61 100644
--- a/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
+++ b/chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc
@@ -11,8 +11,8 @@
 #include "ash/common/frame/default_header_painter.h"
 #include "ash/common/frame/frame_border_hit_test.h"
 #include "ash/common/frame/header_painter_util.h"
-#include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
+#include "ash/shell.h"
 #include "base/feature_list.h"
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profiles_state.h"
@@ -77,11 +77,11 @@ BrowserNonClientFrameViewAsh::BrowserNonClientFrameViewAsh(
       window_icon_(nullptr) {
   ash::WmWindow::Get(frame->GetNativeWindow())
       ->InstallResizeHandleWindowTargeter(nullptr);
-  ash::WmShell::Get()->AddShellObserver(this);
+  ash::Shell::GetInstance()->AddShellObserver(this);
 }
 
 BrowserNonClientFrameViewAsh::~BrowserNonClientFrameViewAsh() {
-  ash::WmShell::Get()->RemoveShellObserver(this);
+  ash::Shell::GetInstance()->RemoveShellObserver(this);
 }
 
 void BrowserNonClientFrameViewAsh::Init() {