GitLab

- Modifies iOS implementation of chrome://ukm to use WebUI.
- Refactors HTML/JS resources to be used in iOS.
- Removes method in ukm::UkmDebugDataExtractor that returns HTML debug data.
- Adds helper methods to resolve/reject Promises to WebUIIOS.

Bug: 843181
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I008ce1beb8d35dd9d4a7fc482990f06e3095f16a
Reviewed-on: https://chromium-review.googlesource.com/1147241
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577569}