[Editor] Add an option to use the new 'add an image' flow (bug 1907207)

UX team designed in a new flow we'll implement soon and we want to be able to
make an experiment to be able to compare current flow vs the new one.

web/app.js

@@ -477,6 +477,7 @@ const PDFViewerApplication = {
       enableHighlightFloatingButton: AppOptions.get(
         "enableHighlightFloatingButton"
       ),
+      enableUpdatedAddImage: AppOptions.get("enableUpdatedAddImage"),
       imageResourcesPath: AppOptions.get("imageResourcesPath"),
       enablePrintAutoRotate: AppOptions.get("enablePrintAutoRotate"),
       maxCanvasPixels: AppOptions.get("maxCanvasPixels"),

web/app_options.js

@@ -178,6 +178,14 @@ const defaultOptions = {
     value: typeof PDFJSDev === "undefined" || !PDFJSDev.test("CHROME"),
     kind: OptionKind.VIEWER + OptionKind.PREFERENCE,
   },
+  enableUpdatedAddImage: {
+    // We'll probably want to make some experiments before enabling this
+    // in Firefox release, but it has to be temporary.
+    // TODO: remove it when unnecessary.
+    /** @type {boolean} */
+    value: false,
+    kind: OptionKind.VIEWER + OptionKind.PREFERENCE,
+  },
   externalLinkRel: {
     /** @type {string} */
     value: "noopener noreferrer nofollow",

web/pdf_viewer.js

@@ -219,6 +219,8 @@ class PDFViewer {
 
   #enablePermissions = false;
 
+  #enableUpdatedAddImage = false;
+
   #eventAbortController = null;
 
   #mlManager = null;
@@ -291,6 +293,7 @@ class PDFViewer {
       options.annotationEditorHighlightColors || null;
     this.#enableHighlightFloatingButton =
       options.enableHighlightFloatingButton === true;
+    this.#enableUpdatedAddImage = options.enableUpdatedAddImage === true;
     this.imageResourcesPath = options.imageResourcesPath || "";
     this.enablePrintAutoRotate = options.enablePrintAutoRotate || false;
     if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
@@ -890,6 +893,7 @@ class PDFViewer {
               pageColors,
               this.#annotationEditorHighlightColors,
               this.#enableHighlightFloatingButton,
+              this.#enableUpdatedAddImage,
               this.#mlManager
             );
             eventBus.dispatch("annotationeditoruimanager", {