Storage manager: Add conditional messages for disk low situation and update design.

chrome/browser/ui/webui/options/chromeos/storage_manager_handler.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 CHROME_BROWSER_UI_WEBUI_OPTIONS_CHROMEOS_STORAGE_MANAGER_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_OPTIONS_CHROMEOS_STORAGE_MANAGER_HANDLER_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/ui/webui/options/options_ui.h"
 #include "components/arc/storage_manager/arc_storage_manager.h"
 
 namespace chromeos {
 namespace options {
 
 // Storage manager overlay page UI handler.
 class StorageManagerHandler : public ::options::OptionsPageUIHandler {
  public:
+  // Enumeration for device state about remaining space. These values must be
+  // kept in sync with options.StorageSpaceState in JS code.
+  enum StorageSpaceState {
+    STORAGE_SPACE_NORMAL = 0,
+    STORAGE_SPACE_LOW = 1,
+    STORAGE_SPACE_CRITICALLY_LOW = 2,
+  };
+
   StorageManagerHandler();
   ~StorageManagerHandler() override;
 
   // OptionsPageUIHandler implementation.
   void GetLocalizedValues(base::DictionaryValue* localized_strings) override;
   void InitializePage() override;
 
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
@@ skipping 33 matching lines @@
 
   base::WeakPtrFactory<StorageManagerHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(StorageManagerHandler);
 };
 
 }  // namespace options
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_OPTIONS_CHROMEOS_STORAGE_MANAGER_HANDLER_H_