Replace NotifierSettingsProvider with additions to AshMessageCenterClient api.

Likewise, replace NotifierSettingsObserver with additions to
AshMessageCenterController api.

Adds new mojo type for NotifierId which maps to message_center::NotifierId.
message_center::NotifierUiData isn't used anywhere else, so it's replaced with
(not mapped to) a mojo struct.

NotificationPlatformBridgeChromeOsImpl is now the hub for more things, so it's
moved to its own file and renamed to ChromeAshMessageCenterClient.

Bug: 777649,578868,777493
Change-Id: I04db0d854f0f5aae4ad3a514cc424e35e0e88127
Reviewed-on: https://chromium-review.googlesource.com/736026
Commit-Queue: Evan Stade <[email protected]>
Reviewed-by: Steven Bennetts <[email protected]>
Reviewed-by: Tom Sepez <[email protected]>
Cr-Commit-Position: refs/heads/master@{#513345}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 4ff70bd..43b92fa 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -2721,10 +2721,10 @@
       "metrics/perf/windowed_incognito_observer.h",
       "notifications/arc_application_notifier_controller_chromeos.cc",
       "notifications/arc_application_notifier_controller_chromeos.h",
+      "notifications/chrome_ash_message_center_client.cc",
+      "notifications/chrome_ash_message_center_client.h",
       "notifications/extension_notifier_controller.cc",
       "notifications/extension_notifier_controller.h",
-      "notifications/message_center_settings_controller_chromeos.cc",
-      "notifications/message_center_settings_controller_chromeos.h",
       "notifications/notifier_controller.h",
       "notifications/web_page_notifier_controller.cc",
       "notifications/web_page_notifier_controller.h",