Revert of Moving previews code from components/ to chrome/

components/previews/core/previews_experiments.h

Index: components/previews/core/previews_experiments.h
diff --git a/components/previews/core/previews_experiments.h b/components/previews/core/previews_experiments.h
index a41f02fef613e95581ef9e4840a58c0c0ada3971..0a6f3a6f9a3864cbd5ea96a830600fd63d222f56 100644
--- a/components/previews/core/previews_experiments.h
+++ b/components/previews/core/previews_experiments.h
@@ -52,17 +52,10 @@
 // served.
 net::EffectiveConnectionType EffectiveConnectionTypeThreshold();
 
-// Whether offline previews are enabled.
-bool IsOfflinePreviewsEnabled();
-
-// The blacklist version for offline previews.
-int OfflinePreviewsVersion();
-
 }  // namespace params
 
 enum class PreviewsType {
   NONE = 0,
-  // The user is shown an offline page as a preview.
   OFFLINE = 1,
   // Insert new enum values here. Keep values sequential to allow looping
   // from NONE+1 to LAST-1.
@@ -74,6 +67,17 @@
 // Returns true if any client-side previews experiment is active.
 bool IsIncludedInClientSidePreviewsExperimentsFieldTrial();
 
+// Returns true if the field trial that should enable previews for |type| for
+// prohibitvely slow networks is active.
+bool IsPreviewsTypeEnabled(PreviewsType type);
+
+// Returns the version of preview treatment |type|. Defaults to 0 if not
+// specified in field trial config.
+int GetPreviewsTypeVersion(PreviewsType type);
+
+// Returns the enabled PreviewsTypes with their version.
+std::unique_ptr<PreviewsTypeList> GetEnabledPreviews();
+
 // Sets the appropriate state for field trial and variations to imitate the
 // offline pages field trial.
 bool EnableOfflinePreviewsForTesting();