Detect how to display pdf files

Closes: #1099

modules/webapp/src/main/elm/Comp/ItemDetail/Model.elm

@@ -100,7 +100,6 @@ type alias Model =
     , sentMailsOpen : Bool
     , attachMeta : Dict String Comp.AttachmentMeta.Model
     , attachMetaOpen : Bool
-    , pdfNativeView : Maybe Bool
     , attachModal : Maybe ConfirmModalValue
     , addFilesOpen : Bool
     , addFilesModel : Comp.Dropzone.Model
@@ -236,7 +235,6 @@ emptyModel =
     , sentMailsOpen = False
     , attachMeta = Dict.empty
     , attachMetaOpen = False
-    , pdfNativeView = Nothing
     , attachModal = Nothing
     , addFilesOpen = False
     , addFilesModel = Comp.Dropzone.init []
@@ -316,7 +314,6 @@ type Msg
     | SentMailsResp (Result Http.Error SentMails)
     | AttachMetaClick String
     | AttachMetaMsg String Comp.AttachmentMeta.Msg
-    | TogglePdfNativeView Bool
     | RequestDeleteAttachment String
     | DeleteAttachConfirmed String
     | RequestDeleteSelected

modules/webapp/src/main/elm/Comp/ItemDetail/SingleAttachment.elm

@@ -85,12 +85,8 @@ view texts flags settings model pos attach =
                 , style "max-height" "calc(100vh - 140px)"
                 , style "min-height" "500px"
                 ]
-                [ iframe
-                    [ if Maybe.withDefault settings.nativePdfPreview model.pdfNativeView then
-                        src fileUrl
-
-                      else
-                        src (fileUrl ++ "/view")
+                [ embed
+                    [ src <| Data.UiSettings.pdfUrl settings flags fileUrl
                     , class "absolute h-full w-full top-0 left-0 mx-0 py-0"
                     , id "ds-pdf-view-iframe"
                     ]
@@ -254,18 +250,6 @@ attachHeader texts settings model _ attach =
                                 , classList [ ( "hidden", not attach.converted ) ]
                                 ]
                           }
-                        , { icon =
-                                if Maybe.withDefault settings.nativePdfPreview model.pdfNativeView then
-                                    "fa fa-toggle-on"
-
-                                else
-                                    "fa fa-toggle-off"
-                          , label = texts.renderPdfByBrowser
-                          , attrs =
-                                [ onClick (TogglePdfNativeView settings.nativePdfPreview)
-                                , href "#"
-                                ]
-                          }
                         , { icon =
                                 if isAttachMetaOpen model attach.id then
                                     "fa fa-toggle-on"

modules/webapp/src/main/elm/Comp/ItemDetail/Update.elm

@@ -913,19 +913,6 @@ update key flags inav settings msg model =
                 Nothing ->
                     resultModel model
 
-        TogglePdfNativeView default ->
-            resultModel
-                { model
-                    | pdfNativeView =
-                        case model.pdfNativeView of
-                            Just flag ->
-                                Just (not flag)
-
-                            Nothing ->
-                                Just (not default)
-                    , attachmentDropdownOpen = False
-                }
-
         DeleteAttachConfirmed attachId ->
             let
                 cmd =