Revert of Moving previews code from components/ to chrome/

components/previews/core/previews_io_data.cc

Index: components/previews/core/previews_io_data.cc
diff --git a/components/previews/core/previews_io_data.cc b/components/previews/core/previews_io_data.cc
index 9645fa249513ccc186559024eee32088444a2ec5..0a7af37fda2653d9ddf580fe6411677afb1a1d84 100644
--- a/components/previews/core/previews_io_data.cc
+++ b/components/previews/core/previews_io_data.cc
@@ -51,10 +51,8 @@
 
 void PreviewsIOData::Initialize(
     base::WeakPtr<PreviewsUIService> previews_ui_service,
-    std::unique_ptr<PreviewsOptOutStore> previews_opt_out_store,
-    const PreviewsIsEnabledCallback& is_enabled_callback) {
+    std::unique_ptr<PreviewsOptOutStore> previews_opt_out_store) {
   DCHECK(ui_task_runner_->BelongsToCurrentThread());
-  is_enabled_callback_ = is_enabled_callback;
   previews_ui_service_ = previews_ui_service;
 
   // Set up the IO thread portion of |this|.
@@ -90,16 +88,15 @@
 
 bool PreviewsIOData::ShouldAllowPreview(const net::URLRequest& request,
                                         PreviewsType type) const {
-  if (is_enabled_callback_.is_null() || !previews_black_list_) {
+  if (!IsPreviewsTypeEnabled(type))
+    return false;
+  // The blacklist will disallow certain hosts for periods of time based on
+  // user's opting out of the preview
+  if (!previews_black_list_) {
     LogPreviewsEligibilityReason(
         PreviewsEligibilityReason::BLACKLIST_UNAVAILABLE, type);
     return false;
   }
-  if (!is_enabled_callback_.Run(type))
-    return false;
-
-  // The blacklist will disallow certain hosts for periods of time based on
-  // user's opting out of the preview
   PreviewsEligibilityReason status =
       previews_black_list_->IsLoadedAndAllowed(request.url(), type);
   if (status != PreviewsEligibilityReason::ALLOWED) {