GitLab

Adds the following to DialogModel:
* Support for dialog icons through DialogModel::Builder::SetIcon.
* Support for base::string16 (not message_id) in DialogModelLabel.
* Support for character break in DialogModelLabel.

Then refactors ExtensionUninstallDialogView to use DialogModel, which
required adding the above items to DialogModel.

Bug: 1106422
Change-Id: I59267cf6037f907171f9ff5121c37528b1d1a371
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2454978
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816711}