Wait for the battery level before starting encryption migration.

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

Index: chrome/browser/resources/chromeos/login/encryption_migration.js
diff --git a/chrome/browser/resources/chromeos/login/encryption_migration.js b/chrome/browser/resources/chromeos/login/encryption_migration.js
index f78d68b8fe4ee3e55f65d6736899dde6922efe7b..2fd10d1f3f4f6fc98125b07d3d65ca1bd1d41565 100644
--- a/chrome/browser/resources/chromeos/login/encryption_migration.js
+++ b/chrome/browser/resources/chromeos/login/encryption_migration.js
@@ -50,6 +50,30 @@ Polymer({
       type: Boolean,
       value: false
     },
+
+    /**
+     * Battery level.
+     */
+    batteryPercent: {
+      type: Number,
+      value: 0
+    },
+
+    /**
+     * True if the battery level is enough to start migration.
+     */
+    isEnoughBattery: {
+      type: Boolean,
+      value: true
+    },
+
+    /**
+     * True if the user already accepted the migration.
+     */
+    isMigrationAccepted: {
+      type: Boolean,
+      value: false
+    },
   },
 
   /**