[pull] master from mozilla:master

src/scripting_api/app.js

@@ -152,13 +152,10 @@ class App extends PDFObject {
   }
 
   static _getLanguage(language) {
-    const [main, sub] = language.toLowerCase().split(/[-_]/);
+    const [main, sub] = language.toLowerCase().split(/[-_]/, 2);
     switch (main) {
       case "zh":
-        if (sub === "cn" || sub === "sg") {
-          return "CHS";
-        }
-        return "CHT";
+        return sub === "cn" || sub === "sg" ? "CHS" : "CHT";
       case "da":
         return "DAN";
       case "de":
@@ -178,10 +175,7 @@ class App extends PDFObject {
       case "no":
         return "NOR";
       case "pt":
-        if (sub === "br") {
-          return "PTB";
-        }
-        return "ENU";
+        return sub === "br" ? "PTB" : "ENU";
       case "fi":
         return "SUO";
       case "SV":
@@ -249,13 +243,10 @@ class App extends PDFObject {
   }
 
   get fs() {
-    if (this._fs === null) {
-      this._fs = new Proxy(
-        new FullScreen({ send: this._send }),
-        this._proxyHandler
-      );
-    }
-    return this._fs;
+    return (this._fs ??= new Proxy(
+      new FullScreen({ send: this._send }),
+      this._proxyHandler
+    ));
   }
 
   set fs(_) {
@@ -356,13 +347,10 @@ class App extends PDFObject {
   }
 
   get thermometer() {
-    if (this._thermometer === null) {
-      this._thermometer = new Proxy(
-        new Thermometer({ send: this._send }),
-        this._proxyHandler
-      );
-    }
-    return this._thermometer;
+    return (this._thermometer ??= new Proxy(
+      new Thermometer({ send: this._send }),
+      this._proxyHandler
+    ));
   }
 
   set thermometer(_) {

src/scripting_api/field.js

@@ -453,11 +453,9 @@ class Field extends PDFObject {
       return array;
     }
 
-    if (this._children === null) {
-      this._children = this._document.obj._getTerminalChildren(this._fieldPath);
-    }
-
-    return this._children;
+    return (this._children ??= this._document.obj._getTerminalChildren(
+      this._fieldPath
+    ));
   }
 
   getLock() {

test/integration/thumbnail_view_spec.mjs

@@ -413,6 +413,46 @@ describe("PDF Thumbnail View", () => {
     });
   });
 
+  describe("Views manager status visibility (bug 2016656)", () => {
+    let pages;
+
+    beforeEach(async () => {
+      pages = await loadAndWait(
+        "page_with_number_and_link.pdf",
+        "#viewsManagerToggleButton",
+        null,
+        null,
+        { enableSplitMerge: true }
+      );
+    });
+
+    afterEach(async () => {
+      await closePages(pages);
+    });
+
+    it("should show the manage button in thumbnail view and hide it in outline view", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await page.click("#viewsManagerToggleButton");
+          await waitForThumbnailVisible(page, 1);
+
+          // The status bar (Select pages + Manage button) must be visible in
+          // thumbnail view.
+          await page.waitForSelector("#viewsManagerStatus", { visible: true });
+
+          // Switch to outline view.
+          await page.click("#viewsManagerSelectorButton");
+          await page.waitForSelector("#outlinesViewMenu", { visible: true });
+          await page.click("#outlinesViewMenu");
+          await page.waitForSelector("#outlinesView", { visible: true });
+
+          // The status bar must no longer be visible in outline view.
+          await page.waitForSelector("#viewsManagerStatus", { hidden: true });
+        })
+      );
+    });
+  });
+
   describe("Checkbox keyboard navigation", () => {
     let pages;
 

web/viewer.js

@@ -133,6 +133,7 @@ function getViewerConfiguration() {
       viewsManagerHeaderLabel: document.getElementById(
         "viewsManagerHeaderLabel"
       ),
+      viewsManagerStatus: document.getElementById("viewsManagerStatus"),
       manageMenu: {
         button: document.getElementById("viewsManagerStatusActionButton"),
         menu: document.getElementById("viewsManagerStatusActionOptions"),

web/views_manager.js

@@ -90,6 +90,7 @@ class ViewsManager extends Sidebar {
       viewsManagerSelectorButton,
       viewsManagerSelectorOptions,
       viewsManagerHeaderLabel,
+      viewsManagerStatus,
     },
     eventBus,
     l10n,
@@ -132,6 +133,7 @@ class ViewsManager extends Sidebar {
 
     this.viewsManagerCurrentOutlineButton = viewsManagerCurrentOutlineButton;
     this.viewsManagerHeaderLabel = viewsManagerHeaderLabel;
+    this.viewsManagerStatus = viewsManagerStatus;
 
     this.eventBus = eventBus;
 
@@ -245,6 +247,7 @@ class ViewsManager extends Sidebar {
         return;
     }
 
+    this.viewsManagerStatus.hidden = view !== SidebarView.THUMBS;
     this.viewsManagerCurrentOutlineButton.hidden = view !== SidebarView.OUTLINE;
     this.viewsManagerHeaderLabel.setAttribute(
       "data-l10n-id",