Change Lo-Fi bool to bitmask to support multiple Previews types

content/public/browser/resource_dispatcher_host_delegate.cc

Index: content/public/browser/resource_dispatcher_host_delegate.cc
diff --git a/content/public/browser/resource_dispatcher_host_delegate.cc b/content/public/browser/resource_dispatcher_host_delegate.cc
index 1866eb83bdd45a61785db3267a9570930045305f..25d36c9f3d50157e1d36b9a6d58c7659d65b2390 100644
--- a/content/public/browser/resource_dispatcher_host_delegate.cc
+++ b/content/public/browser/resource_dispatcher_host_delegate.cc
@@ -7,6 +7,7 @@
 #include "content/public/browser/navigation_data.h"
 #include "content/public/browser/resource_request_info.h"
 #include "content/public/browser/stream_info.h"
+#include "content/public/common/previews_state.h"
 #include "net/ssl/client_cert_store.h"
 
 namespace content {
@@ -87,10 +88,10 @@ void ResourceDispatcherHostDelegate::RequestComplete(
 void ResourceDispatcherHostDelegate::RequestComplete(
     net::URLRequest* url_request) {}
 
-bool ResourceDispatcherHostDelegate::ShouldEnableLoFiMode(
+int ResourceDispatcherHostDelegate::GetPreviewsState(
     const net::URLRequest& url_request,
     content::ResourceContext* resource_context) {
-  return false;
+  return PREVIEWS_UNSPECIFIED;
 }
 
 NavigationData* ResourceDispatcherHostDelegate::GetNavigationData(