Remove use of deprecated base::ListValue::Append(Value*) overload in //chrome/browser/ui/ash

CreateAppDict()'s return value is passed to Append(); just change
it to return a std::unique_ptr<base::Value> instead of a
base::Value*.

BUG=581865

Review-Url: https://codereview.chromium.org/2416963002
Cr-Commit-Position: refs/heads/master@{#425413}
2 files changed