mash: Remove ShelfDelegate; move functions to ShelfModel.

ash/test/shell_test_api.cc

Index: ash/test/shell_test_api.cc
diff --git a/ash/test/shell_test_api.cc b/ash/test/shell_test_api.cc
index 3bc0b30f2a8ba1a4875f00670e4a0e389d4d3602..a60db9e77491067033aec18aacb3d49745bf9e4c 100644
--- a/ash/test/shell_test_api.cc
+++ b/ash/test/shell_test_api.cc
@@ -7,7 +7,6 @@
 #include "ash/palette_delegate.h"
 #include "ash/root_window_controller.h"
 #include "ash/session/session_state_delegate.h"
-#include "ash/shelf/shelf_delegate.h"
 #include "ash/shell.h"
 
 namespace ash {
@@ -47,10 +46,5 @@ void ShellTestApi::SetSessionStateDelegate(
   shell_->session_state_delegate_.reset(session_state_delegate);
 }
 
-void ShellTestApi::SetShelfDelegate(
-    std::unique_ptr<ShelfDelegate> test_delegate) {
-  shell_->shelf_delegate_ = std::move(test_delegate);
-}
-
 }  // namespace test
 }  // namespace ash