[stts-notifs] Move chrome/browser/sharing to components/sharing_message

This CL moves SharingService and it's dependencies to the components
directory.

This is mostly a clean move, with some exceptions:
* To remove the dependencies on BrowserThread, SingleThreadTaskRunners
  are injected into SharingService and SharingMessageSender. The
  TaskRunner in SharingService is also changed from BEST_EFFORT to
  USER_VISIBLE.
* SharingDeviceRegistration is made a virtual class and implemented
  separately in chrome/browser and ios/ due to a dependency on
  chrome/android/

Bug: 353708939
Change-Id: Ic4c8a7f91f947a6db3f58a50ee6806e9e956320d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5718879
Reviewed-by: Josh Horwich <[email protected]>
Commit-Queue: Hira Mahmood <[email protected]>
Reviewed-by: Rushan Suleymanov <[email protected]>
Reviewed-by: Cait Phillips <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1335472}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 4f5f4ec..4283b07 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -70,7 +70,6 @@
 #include "chrome/browser/push_messaging/push_messaging_service_impl.h"
 #include "chrome/browser/rlz/chrome_rlz_tracker_delegate.h"
 #include "chrome/browser/search/search.h"
-#include "chrome/browser/sharing/sharing_sync_preference.h"
 #include "chrome/browser/sharing_hub/sharing_hub_features.h"
 #include "chrome/browser/ssl/ssl_config_service_manager.h"
 #include "chrome/browser/task_manager/task_manager_interface.h"
@@ -98,6 +97,7 @@
 #include "chrome/browser/ui/webui/policy/policy_ui.h"
 #include "chrome/browser/ui/webui/print_preview/policy_settings.h"
 #include "components/privacy_sandbox/tpcd_pref_names.h"
+#include "components/sharing_message/sharing_sync_preference.h"
 #if BUILDFLAG(IS_CHROMEOS_ASH)
 #include "chrome/browser/ui/webui/settings/reset_settings_handler.h"
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)