Remove ManagePasswordsUIController::NavigateToSmartLockPage

Replace it with the equivalent ManagePasswordsUIController::NavigateToExternalPasswordManager.

Note: This CL does not remove IDS_PASSWORD_MANAGER_SMART_LOCK_PAGE yet, because it is also used in other pieces of the password manager UI. We need to double-check if it is OK to merge that with chrome::kPasswordManagerAccountDashboardURL, or whether it just should be made a separate constant. Using localisation to get the hl= URL parameter is very likely an overkill, see #0 in http://crbug.com/548259.

R=vasilii@chromium.org
BUG=548259

Review URL: https://codereview.chromium.org/1467993002

Cr-Original-Commit-Position: refs/heads/master@{#361304}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1bff66d12e811993940e7dd01074768c30e0cd5b

ios/grit_whitelist.txt

@@ -597,7 +597,6 @@ IDS_PASSWORDS_SHOW_PASSWORDS_TAB_TITLE
 IDS_PASSWORD_MANAGER_BLACKLIST_BUTTON
 IDS_PASSWORD_MANAGER_SAVE_BUTTON
 IDS_PASSWORD_MANAGER_SMART_LOCK
-IDS_PASSWORD_MANAGER_SMART_LOCK_PAGE
 IDS_PAST_TIME_TODAY
 IDS_PAST_TIME_YESTERDAY
 IDS_PDF_INFOBAR_ALWAYS_USE_READER_BUTTON