arc: Message for a low-battery case of migration notification.

chrome/browser/chromeos/arc/arc_migration_constants.h

Index: chrome/browser/chromeos/arc/arc_migration_constants.h
diff --git a/chrome/browser/chromeos/arc/arc_migration_constants.h b/chrome/browser/chromeos/arc/arc_migration_constants.h
new file mode 100644
index 0000000000000000000000000000000000000000..eeee1ad56b7887e0b3faff184a00e459a2a9f0db
--- /dev/null
+++ b/chrome/browser/chromeos/arc/arc_migration_constants.h
@@ -0,0 +1,15 @@
+// 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_ARC_ARC_MIGRATION_CONSTANTS_H_
+#define CHROME_BROWSER_CHROMEOS_ARC_ARC_MIGRATION_CONSTANTS_H_
+
+namespace arc {
+
+// The minimum battery level to start the migration.
+constexpr double kMigrationMinimumBatteryPercent = 30;
+
+}  // namespace arc
+
+#endif  // CHROME_BROWSER_CHROMEOS_ARC_ARC_MIGRATION_CONSTANTS_H_