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 78628ef0eed0812da7a1caaf00f0573ff525c128..8b1a59ca06e17b9beaaca62b19aa82ce2def8744 100644
--- a/content/public/browser/resource_dispatcher_host_delegate.cc
+++ b/content/public/browser/resource_dispatcher_host_delegate.cc
@@ -86,10 +86,10 @@ void ResourceDispatcherHostDelegate::RequestComplete(
 void ResourceDispatcherHostDelegate::RequestComplete(
     net::URLRequest* url_request) {}
 
-bool ResourceDispatcherHostDelegate::ShouldEnableLoFiMode(
+PreviewsState ResourceDispatcherHostDelegate::GetPreviewsState(
     const net::URLRequest& url_request,
     content::ResourceContext* resource_context) {
-  return false;
+  return PREVIEWS_UNSPECIFIED;
 }
 
 NavigationData* ResourceDispatcherHostDelegate::GetNavigationData(