Add support to previews/ for Server LoFi and LitePages

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 7dd7bc2c42c574b296c58ff2391d1e556530a59a..38a4511dc0ba55cbc7b270cf53c7c9e3faaa3dd5 100644
--- a/components/previews/core/previews_experiments.h
+++ b/components/previews/core/previews_experiments.h
@@ -5,6 +5,7 @@
 #ifndef COMPONENTS_PREVIEWS_CORE_PREVIEWS_EXPERIMENTS_H_
 #define COMPONENTS_PREVIEWS_CORE_PREVIEWS_EXPERIMENTS_H_
 
+#include <string>
 #include <utility>
 #include <vector>
 
@@ -78,9 +79,15 @@ enum class PreviewsType {
   // Replace images with placeholders generated on the client.
   CLIENT_LOFI = 2,
 
+  // The user is shown a server lite page.
+  LITE_PAGE = 3,
+
+  // The user is shown a server LoFi page.
+  SERVER_LOFI = 4,
+
   // Insert new enum values here. Keep values sequential to allow looping
   // from NONE+1 to LAST-1.
-  LAST = 3,
+  LAST = 5,
 };
 
 typedef std::vector<std::pair<PreviewsType, int>> PreviewsTypeList;
@@ -88,6 +95,9 @@ typedef std::vector<std::pair<PreviewsType, int>> PreviewsTypeList;
 // Returns true if any client-side previews experiment is active.
 bool IsIncludedInClientSidePreviewsExperimentsFieldTrial();
 
+// Gets the string representation of |type|.
+std::string GetStringNameForType(PreviewsType type);
+
 }  // namespace previews
 
 #endif  // COMPONENTS_PREVIEWS_CORE_PREVIEWS_EXPERIMENTS_H_