chromeos: Rename ash::WmShelf to Shelf

ash/test/ash_test_base.h

Index: ash/test/ash_test_base.h
diff --git a/ash/test/ash_test_base.h b/ash/test/ash_test_base.h
index ddcb800b525c174952e9d3c7e90bfc258ba07e07..1a107fb2eb320c8a06bd908a90e0d7d8f52b470d 100644
--- a/ash/test/ash_test_base.h
+++ b/ash/test/ash_test_base.h
@@ -49,8 +49,8 @@ class WidgetDelegate;
 }
 
 namespace ash {
+class Shelf;
 class SystemTray;
-class WmShelf;
 
 namespace test {
 
@@ -69,8 +69,8 @@ class AshTestBase : public testing::Test {
   void SetUp() override;
   void TearDown() override;
 
-  // Returns the WmShelf for the primary display.
-  static WmShelf* GetPrimaryShelf();
+  // Returns the Shelf for the primary display.
+  static Shelf* GetPrimaryShelf();
 
   // Returns the system tray on the primary display.
   static SystemTray* GetPrimarySystemTray();