[api-minor] Support the Content-Disposition filename in the Firefox PDF Viewer (bug 1694556, PR 9379 follow-up)

As can be seen [in the mozilla-central code](https://searchfox.org/mozilla-central/rev/a6db3bd67367aa9ddd9505690cab09b47e65a762/toolkit/components/pdfjs/content/PdfStreamConverter.jsm#1222-1225), we're already getting the Content-Disposition filename. However, that data isn't passed through to the viewer nor to the `PDFDataTransportStream`-implementation, which explains why it's currently being ignored.

*Please note:* This will also require a small mozilla-central patch, see https://bugzilla.mozilla.org/show_bug.cgi?id=1694556, to forward the necessary data to the viewer.

web/app.js

@@ -44,6 +44,7 @@ import {
   getFilenameFromUrl,
   GlobalWorkerOptions,
   InvalidPDFException,
+  isPdfFile,
   LinkTarget,
   loadScript,
   MissingPDFException,
@@ -727,7 +728,10 @@ const PDFViewerApplication = {
       onOpenWithTransport: (url, length, transport) => {
         this.open(url, { length, range: transport });
       },
-      onOpenWithData: data => {
+      onOpenWithData: (data, contentDispositionFilename) => {
+        if (isPdfFile(contentDispositionFilename)) {
+          this._contentDispositionFilename = contentDispositionFilename;
+        }
         this.open(data);
       },
       onOpenWithURL: (url, length, originalUrl) => {
@@ -1744,7 +1748,7 @@ const PDFViewerApplication = {
     }
     this.documentInfo = info;
     this.metadata = metadata;
-    this._contentDispositionFilename = contentDispositionFilename;
+    this._contentDispositionFilename ??= contentDispositionFilename;
     this._contentLength ??= contentLength; // See `getDownloadInfo`-call above.
 
     // Provides some basic debug information

web/download_manager.js

@@ -13,8 +13,7 @@
  * limitations under the License.
  */
 
-import { createObjectURL, createValidAbsoluteUrl } from "pdfjs-lib";
-import { PdfFileRegExp } from "./ui_utils.js";
+import { createObjectURL, createValidAbsoluteUrl, isPdfFile } from "pdfjs-lib";
 import { viewerCompatibilityParams } from "./viewer_compatibility.js";
 
 if (typeof PDFJSDev !== "undefined" && !PDFJSDev.test("CHROME || GENERIC")) {
@@ -68,10 +67,10 @@ class DownloadManager {
    * @returns {boolean} Indicating if the data was opened.
    */
   openOrDownloadData(element, data, filename) {
-    const isPdfFile = PdfFileRegExp.test(filename);
-    const contentType = isPdfFile ? "application/pdf" : "";
+    const isPdfData = isPdfFile(filename);
+    const contentType = isPdfData ? "application/pdf" : "";
 
-    if (isPdfFile && !viewerCompatibilityParams.disableCreateObjectURL) {
+    if (isPdfData && !viewerCompatibilityParams.disableCreateObjectURL) {
       let blobUrl = this._openBlobUrls.get(element);
       if (!blobUrl) {
         blobUrl = URL.createObjectURL(new Blob([data], { type: contentType }));

web/firefoxcom.js

@@ -14,10 +14,10 @@
  */
 
 import "../extensions/firefox/tools/l10n.js";
-import { DEFAULT_SCALE_VALUE, PdfFileRegExp } from "./ui_utils.js";
 import { DefaultExternalServices, PDFViewerApplication } from "./app.js";
-import { PDFDataRangeTransport, shadow } from "pdfjs-lib";
+import { isPdfFile, PDFDataRangeTransport, shadow } from "pdfjs-lib";
 import { BasePreferences } from "./preferences.js";
+import { DEFAULT_SCALE_VALUE } from "./ui_utils.js";
 
 if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
   throw new Error(
@@ -129,10 +129,10 @@ class DownloadManager {
    * @returns {boolean} Indicating if the data was opened.
    */
   openOrDownloadData(element, data, filename) {
-    const isPdfFile = PdfFileRegExp.test(filename);
-    const contentType = isPdfFile ? "application/pdf" : "";
+    const isPdfData = isPdfFile(filename);
+    const contentType = isPdfData ? "application/pdf" : "";
 
-    if (isPdfFile) {
+    if (isPdfData) {
       let blobUrl = this._openBlobUrls.get(element);
       if (!blobUrl) {
         blobUrl = URL.createObjectURL(new Blob([data], { type: contentType }));
@@ -332,7 +332,8 @@ class FirefoxExternalServices extends DefaultExternalServices {
           pdfDataRangeTransport = new FirefoxComDataRangeTransport(
             args.length,
             args.data,
-            args.done
+            args.done,
+            args.filename
           );
 
           callbacks.onOpenWithTransport(
@@ -367,7 +368,7 @@ class FirefoxExternalServices extends DefaultExternalServices {
             callbacks.onError(args.errorCode);
             break;
           }
-          callbacks.onOpenWithData(args.data);
+          callbacks.onOpenWithData(args.data, args.filename);
           break;
       }
     });

web/pdf_attachment_viewer.js

@@ -119,8 +119,8 @@ class PDFAttachmentViewer extends BaseTreeViewer {
     let attachmentsCount = 0;
     for (const name of names) {
       const item = attachments[name];
-      const content = item.content;
-      const filename = getFilenameFromUrl(item.filename);
+      const content = item.content,
+        filename = getFilenameFromUrl(item.filename);
 
       const div = document.createElement("div");
       div.className = "treeItem";

web/ui_utils.js

@@ -69,9 +69,6 @@ const SpreadMode = {
 // Used by `PDFViewerApplication`, and by the API unit-tests.
 const AutoPrintRegExp = /\bprint\s*\(/;
 
-// Used by the (various) `DownloadManager`-implementations.
-const PdfFileRegExp = /\.pdf$/i;
-
 // Replaces {{arguments}} with their values.
 function formatL10nValue(text, args) {
   if (!args) {
@@ -1062,7 +1059,6 @@ export {
   normalizeWheelEventDirection,
   NullL10n,
   parseQueryString,
-  PdfFileRegExp,
   PresentationModeState,
   ProgressBar,
   RendererType,