chromeos: Remove AshTestBase::SupportsMultipleDisplays

ash/test/ash_test_impl_aura.h

 // Copyright 2016 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 ASH_MUS_TEST_ASH_TEST_IMPL_AURA_H_
 #define ASH_MUS_TEST_ASH_TEST_IMPL_AURA_H_
 
 #include "ash/common/test/ash_test_impl.h"
 
 namespace ash {
 namespace test {
 class AshTestBase;
 }
 
 // Implementation of AshTestImpl on top of aura. Implementation of AshTestImpl
 // calls through to AshTestBase.
 class AshTestImplAura : public AshTestImpl {
  public:
   AshTestImplAura();
   ~AshTestImplAura() override;
 
   // AshTestImpl:
   void SetUp() override;
   void TearDown() override;
-  bool SupportsMultipleDisplays() const override;
   void UpdateDisplay(const std::string& display_spec) override;
   std::unique_ptr<WindowOwner> CreateTestWindow(
       const gfx::Rect& bounds_in_screen,
       ui::wm::WindowType type,
       int shell_window_id) override;
   std::unique_ptr<WindowOwner> CreateToplevelTestWindow(
       const gfx::Rect& bounds_in_screen,
       int shell_window_id) override;
   display::Display GetSecondaryDisplay() override;
   bool SetSecondaryDisplayPlacement(
       display::DisplayPlacement::Position position,
       int offset) override;
   void ConfigureWidgetInitParamsForDisplay(
       WmWindow* window,
       views::Widget::InitParams* init_params) override;
   void AddTransientChild(WmWindow* parent, WmWindow* window) override;
 
  private:
   std::unique_ptr<test::AshTestBase> ash_test_base_;
 
   DISALLOW_COPY_AND_ASSIGN(AshTestImplAura);
 };
 
 }  // namespace ash
 
 #endif  // ASH_MUS_TEST_ASH_TEST_IMPL_AURA_H_