Check the available storage size before starting encryption migration.

chrome/browser/resources/chromeos/login/encryption_migration.js

 // Copyright 2017 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.
 
 /**
  * @fileoverview Polymer element for displaying encryption migration screen.
  */
 
 /**
  * Enum for the UI states corresponding to sub steps inside migration screen.
  * These values must be kept in sync with
  * EncryptionMigrationScreenHandler::UIState in C++ code.
  * @enum {number}
  */
 var EncryptionMigrationUIState = {
   INITIAL: 0,
-  MIGRATING: 1,
-  MIGRATION_SUCCEEDED: 2,
-  MIGRATION_FAILED: 3
+  READY: 1,
+  MIGRATING: 2,
+  MIGRATION_SUCCEEDED: 3,
+  MIGRATION_FAILED: 4,
+  NOT_ENOUGH_SPACE: 5
 };
 
 Polymer({
   is: 'encryption-migration',
 
   properties: {
     /**
      * Current UI state which corresponds to a sub step in migration process.
      * @type {EncryptionMigrationUIState}
      */
     uiState: {
       type: Number,
       value: 0
     },
 
     /**
      * Current migration progress in range [0, 1]. Negative value means that
      * the progress is unknown.
      */
     progress: {
       type: Number,
       value: -1
     },
+
+    /**
+     * Whether the current migration is resuming the previous one.
+     */
+    isResuming: {
+      type: Boolean,
+      value: false
+    },
   },
 
   /**
    * Returns true if the migration is in initial state.
    * @param {EncryptionMigrationUIState} state Current UI state
    * @private
    */
   isInitial_: function(state) {
     return state == EncryptionMigrationUIState.INITIAL;
   },
 
   /**
+   * Returns true if the migration is ready to start.
+   * @param {EncryptionMigrationUIState} state Current UI state
+   * @private
+   */
+  isReady_: function(state) {
+    return state == EncryptionMigrationUIState.READY;
+  },
+
+  /**
    * Returns true if the migration is in progress.
    * @param {EncryptionMigrationUIState} state Current UI state
    * @private
    */
   isMigrating_: function(state) {
     return state == EncryptionMigrationUIState.MIGRATING;
   },
 
   /**
    * Returns true if the migration is finished successfully.
    * @param {EncryptionMigrationUIState} state Current UI state
    * @private
    */
   isMigrationSucceeded_: function(state) {
     return state == EncryptionMigrationUIState.MIGRATION_SUCCEEDED;
   },
 
   /**
    * Returns true if the migration failed.
    * @param {EncryptionMigrationUIState} state Current UI state
    * @private
    */
   isMigrationFailed_: function(state) {
     return state == EncryptionMigrationUIState.MIGRATION_FAILED;
   },
 
   /**
+   * Returns true if the available space is not enough to start migration.
+   * @param {EncryptionMigrationUIState} state Current UI state
+   * @private
+   */
+  isNotEnoughSpace_: function(state) {
+    return state == EncryptionMigrationUIState.NOT_ENOUGH_SPACE;
+  },
+
+  /**
    * Returns true if the current migration progress is unknown.
    * @param {number} progress
    * @private
    */
   isProgressIndeterminate_: function(progress) {
     return progress < 0;
   },
 
   /**
    * Handles tap on UPGRADE button.
@@ skipping 12 matching lines @@
   },
 
   /**
    * Handles tap on RESTART button.
    * @private
    */
   onRestart_: function() {
     this.fire('restart');
   },
 });