ash: Remove WmShelf::ForPrimaryDisplay

ash/common/shelf/wm_shelf.h

Index: ash/common/shelf/wm_shelf.h
diff --git a/ash/common/shelf/wm_shelf.h b/ash/common/shelf/wm_shelf.h
index d1011d06a5d8488a0bf54459a4757d14f61693da..198f9cf27f5b42f0a182b5893db2cb5f97b503f8 100644
--- a/ash/common/shelf/wm_shelf.h
+++ b/ash/common/shelf/wm_shelf.h
@@ -25,11 +25,6 @@ class WmWindow;
 // Used for accessing global state.
 class ASH_EXPORT WmShelf {
  public:
-  // Returns the shelf for the primary display. Useful in tests that only use
-  // a single display. In production code use WmRootWindowController::GetShelf()
-  // with the appropriate display's root window controller.
-  static WmShelf* ForPrimaryDisplay();
-
   // Returns the window showing the shelf.
   virtual WmWindow* GetWindow() = 0;