Rename avatar_url to icon_url in PasswordForm.
As specified in https://w3c.github.io/webappsec/specs/credentialmanagement/#credential
Do not rename it in the password store backends and sync yet:
- native_backend_gnome_x: string_attr_map["avatar_url"]
- native_backend_kwallet_x: {no names, just order}
- native_backend_libsecret: secret_password_store_sync(..., "avatar_url", ...)
- login_database: "CREATE TABLE ... avatar_url ..."
- password_syncable_service: password_specifics->set_avatar_url(...)
These changes will be done in follow-up CLs.
BASE=
1209953002
BUG=505445
Review URL: https://codereview.chromium.org/
1220713005
Cr-Commit-Position: refs/heads/master@{#340096}