Remove unused |context| from GetDefaultParent().

ui/wm/test/wm_test_helper.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_WM_TEST_WM_TEST_HELPER_H_
 #define UI_WM_TEST_WM_TEST_HELPER_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 30 matching lines @@
 // the ash parts of the code.
 class WMTestHelper : public aura::client::WindowParentingClient {
  public:
   WMTestHelper(const gfx::Size& default_window_size,
                ui::ContextFactory* context_factory);
   ~WMTestHelper() override;
 
   aura::WindowTreeHost* host() { return host_.get(); }
 
   // Overridden from client::WindowParentingClient:
-  aura::Window* GetDefaultParent(aura::Window* context,
-                                 aura::Window* window,
+  aura::Window* GetDefaultParent(aura::Window* window,
                                  const gfx::Rect& bounds) override;
 
  private:
   std::unique_ptr<WMState> wm_state_;
   std::unique_ptr<aura::WindowTreeHost> host_;
   std::unique_ptr<aura::InputMethodGlue> input_method_glue_;
   std::unique_ptr<wm::CompoundEventFilter> root_window_event_filter_;
   std::unique_ptr<aura::client::DefaultCaptureClient> capture_client_;
   std::unique_ptr<aura::client::FocusClient> focus_client_;
 
   DISALLOW_COPY_AND_ASSIGN(WMTestHelper);
 };
 
 }  // namespace wm
 
 #endif  // UI_WM_TEST_WM_TEST_HELPER_H_