1) Add 'to Google Drive' link to the all-backed-up message.
2) Don't show details header panel once user has completed import.
3) Introduce a local storage wrapper and make all existing importer uses of chrome.storage.local use this...much shorter and safer.
4) Auto-hide details panel when user clicks out.
5) Fix jank on the panel transition (and switch to vertical swoosh).
BUG=
420680
TEST=browser_test: FileManagerJsTest.*
Committed:
https://crrev.com/8999968bbe5a44fe9e0ce92912e4201abc77ec5e
Cr-Commit-Position: refs/heads/master@{#316993}