[MD Bookmarks] Separate single vs plural messages in toasts.

This CL separates the single and plural messages for copying and deleting
items. This is necessary because mixing $1 style placeholders with
ICU style plural formatting was providing translators with a string that
excluded the placeholder. This then broke when the translated string
was fed into a build, because it was missing the placeholder.

Bug: 741195
Change-Id: Ib4bb619081282c9b497c7363c1a2b72252e3252f
Reviewed-on: https://chromium-review.googlesource.com/572478
Commit-Queue: calamity <[email protected]>
Reviewed-by: Tim Sergeant <[email protected]>
Cr-Commit-Position: refs/heads/master@{#487346}
3 files changed