Remove stale includes from WebHistoryServiceFactory

Neither SigninManager nor ProfileOAuth2TokenService are in use anymore,
we can safely remove them.

Bug: 885174
Change-Id: I9ea858295b2bb868b7a8bdbb73ec34927041fbac
Reviewed-on: https://chromium-review.googlesource.com/c/1288438
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601086}

chrome/browser/history/web_history_service_factory.cc

@@ -8,8 +8,6 @@
 #include "chrome/browser/sync/profile_sync_service_factory.h"
 #include "components/history/core/browser/web_history_service.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
-#include "components/signin/core/browser/profile_oauth2_token_service.h"
-#include "components/signin/core/browser/signin_manager.h"
 #include "components/sync/driver/sync_service.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/storage_partition.h"