diff --git a/web/app.js b/web/app.js
index 8cefd7e56..ff1722148 100644
--- a/web/app.js
+++ b/web/app.js
@@ -16,6 +16,8 @@
 
 import {
   animationStarted,
+  apiPageLayoutToSpreadMode,
+  apiPageModeToSidebarView,
   AutoPrintRegExp,
   DEFAULT_SCALE_VALUE,
   EventBus,
@@ -3350,53 +3352,6 @@ function beforeUnload(evt) {
   return false;
 }
 
-/**
- * Converts API PageLayout values to the format used by `PDFViewer`.
- * NOTE: This is supported to the extent that the viewer implements the
- *       necessary Scroll/Spread modes (since SinglePage, TwoPageLeft,
- *       and TwoPageRight all suggests using non-continuous scrolling).
- * @param {string} mode - The API PageLayout value.
- * @returns {number} A value from {SpreadMode}.
- */
-function apiPageLayoutToSpreadMode(layout) {
-  switch (layout) {
-    case "SinglePage":
-    case "OneColumn":
-      return SpreadMode.NONE;
-    case "TwoColumnLeft":
-    case "TwoPageLeft":
-      return SpreadMode.ODD;
-    case "TwoColumnRight":
-    case "TwoPageRight":
-      return SpreadMode.EVEN;
-  }
-  return SpreadMode.NONE; // Default value.
-}
-
-/**
- * Converts API PageMode values to the format used by `PDFSidebar`.
- * NOTE: There's also a "FullScreen" parameter which is not possible to support,
- *       since the Fullscreen API used in browsers requires that entering
- *       fullscreen mode only occurs as a result of a user-initiated event.
- * @param {string} mode - The API PageMode value.
- * @returns {number} A value from {SidebarView}.
- */
-function apiPageModeToSidebarView(mode) {
-  switch (mode) {
-    case "UseNone":
-      return SidebarView.NONE;
-    case "UseThumbs":
-      return SidebarView.THUMBS;
-    case "UseOutlines":
-      return SidebarView.OUTLINE;
-    case "UseAttachments":
-      return SidebarView.ATTACHMENTS;
-    case "UseOC":
-      return SidebarView.LAYERS;
-  }
-  return SidebarView.NONE; // Default value.
-}
-
 /* Abstract factory for the print service. */
 const PDFPrintServiceFactory = {
   instance: {
diff --git a/web/ui_utils.js b/web/ui_utils.js
index addfb90f9..c90bfd428 100644
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@@ -1001,8 +1001,57 @@ function getActiveOrFocusedElement() {
   return curActiveOrFocused;
 }
 
+/**
+ * Converts API PageLayout values to the format used by `BaseViewer`.
+ * NOTE: This is supported to the extent that the viewer implements the
+ *       necessary Scroll/Spread modes (since SinglePage, TwoPageLeft,
+ *       and TwoPageRight all suggests using non-continuous scrolling).
+ * @param {string} mode - The API PageLayout value.
+ * @returns {number} A value from {SpreadMode}.
+ */
+function apiPageLayoutToSpreadMode(layout) {
+  switch (layout) {
+    case "SinglePage":
+    case "OneColumn":
+      return SpreadMode.NONE;
+    case "TwoColumnLeft":
+    case "TwoPageLeft":
+      return SpreadMode.ODD;
+    case "TwoColumnRight":
+    case "TwoPageRight":
+      return SpreadMode.EVEN;
+  }
+  return SpreadMode.NONE; // Default value.
+}
+
+/**
+ * Converts API PageMode values to the format used by `PDFSidebar`.
+ * NOTE: There's also a "FullScreen" parameter which is not possible to support,
+ *       since the Fullscreen API used in browsers requires that entering
+ *       fullscreen mode only occurs as a result of a user-initiated event.
+ * @param {string} mode - The API PageMode value.
+ * @returns {number} A value from {SidebarView}.
+ */
+function apiPageModeToSidebarView(mode) {
+  switch (mode) {
+    case "UseNone":
+      return SidebarView.NONE;
+    case "UseThumbs":
+      return SidebarView.THUMBS;
+    case "UseOutlines":
+      return SidebarView.OUTLINE;
+    case "UseAttachments":
+      return SidebarView.ATTACHMENTS;
+    case "UseOC":
+      return SidebarView.LAYERS;
+  }
+  return SidebarView.NONE; // Default value.
+}
+
 export {
   animationStarted,
+  apiPageLayoutToSpreadMode,
+  apiPageModeToSidebarView,
   approximateFraction,
   AutoPrintRegExp,
   backtrackBeforeAllVisibleElements, // only exported for testing