chromeos: Rename ash::WmShelf to Shelf

The "Wm" porting layer is being removed, so it can go back to its
original name.

No behavior changes, just a mechanical refactor.

tools/git/move_source_file.py for
    wm_shelf.h to shelf.h
    wm_shelf.cc to shelf.cc
    wm_shelf_observer.h to shelf_observer.h

tools/git/mffr.py for
  WmShelfObserver to ShelfObserver
  WmShelf to Shelf
  wm_shelf to shelf

Fix up a couple call sites like "wm_shelf_container" window.

Replace deprecated GetAlignment() with alignment() because it touches
the same lines as the rest of this change.

BUG=none
TEST=compiles, ash_unittests, chrome unit_tests
[email protected], [email protected]
[email protected], [email protected]

Review-Url: https://codereview.chromium.org/2899253002 .
Cr-Commit-Position: refs/heads/master@{#474526}
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index 7a3caf47..218e00b 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -37,10 +37,10 @@
 class GPUSupport;
 class PaletteDelegate;
 class SessionStateDelegate;
-class SystemTrayDelegate;
+class Shelf;
 struct ShelfItem;
+class SystemTrayDelegate;
 class WallpaperDelegate;
-class WmShelf;
 class WmWindow;
 
 // Delegate of the Shell.
@@ -107,9 +107,9 @@
 
   virtual std::unique_ptr<PaletteDelegate> CreatePaletteDelegate() = 0;
 
-  // Creates a menu model for the |wm_shelf| and optional shelf |item|.
+  // Creates a menu model for the |shelf| and optional shelf |item|.
   // If |item| is null, this creates a context menu for the wallpaper or shelf.
-  virtual ui::MenuModel* CreateContextMenu(WmShelf* wm_shelf,
+  virtual ui::MenuModel* CreateContextMenu(Shelf* shelf,
                                            const ShelfItem* item) = 0;
 
   // Creates a GPU support object. Shell takes ownership of the object.