Adds ash::MaterialDesignController

ash/material_design/material_design_controller.h

Index: ash/material_design/material_design_controller.h
diff --git a/ash/material_design/material_design_controller.h b/ash/material_design/material_design_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..81a28c1da0bbef05ff2ea98f560542b060bcc137
--- /dev/null
+++ b/ash/material_design/material_design_controller.h
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+// 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_MATERIAL_DESIGN_MATERIAL_DESIGN_CONTROLLER_H_
+#define ASH_MATERIAL_DESIGN_MATERIAL_DESIGN_CONTROLLER_H_
+
+#include "ash/ash_export.h"
+#include "base/macros.h"
+
+namespace ash {
+
+namespace test {
+class MaterialDesignControllerTestAPI;
+}  // namespace test
+
+// Central controller to handle material design modes.
+class ASH_EXPORT MaterialDesignController {
+ public:
+  // Initializes |mode_|. Must be called before calling IsMaterial().
+  static void Initialize();
+
+  // Returns true if Material Design is enabled in Chrome OS system UI.
+  // Maps to "ash-enable-md" and "ash-diable-md flags" pair of flags.
+  // Returns false if both flags are specified in command line.
+  static bool IsMaterial();
+
+ private:
+  friend class test::MaterialDesignControllerTestAPI;
+
+  // Tracks whether |mode_| has been initialized. This is necessary so tests can
+  // reset the state back to a clean state during tear down.
+  static bool is_mode_initialized_;
+
+  // True if Material Design is enabled in Chrome OS system UI.
+  static bool mode_;
+
+  // Declarations only. Do not allow construction of an object.
+  MaterialDesignController();
+  ~MaterialDesignController();
+
+  // Returns the per-platform default material design variant.
+  static bool DefaultMode();
+
+  // Sets |mode_| to |mode| and updates |is_mode_initialized_| to true. Can be
+  // used by tests to directly set the mode.
+  static void SetMode(bool mode);
+
+  // Resets the initialization state to uninitialized. To be used by tests to
+  // allow calling Initialize() more than once.
+  static void Uninitialize();
+
+  DISALLOW_COPY_AND_ASSIGN(MaterialDesignController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_MATERIAL_DESIGN_MATERIAL_DESIGN_CONTROLLER_H_