Set title using logic similar as download name

The download method (and the PDF document properties) detect the
file name using `getPDFFileNameFromURL`. The title ought to also
display the PDF filename if available.

web/app.js

@@ -569,14 +569,17 @@ var PDFViewerApplication = {
   setTitleUsingUrl: function pdfViewSetTitleUsingUrl(url) {
     this.url = url;
     this.baseUrl = url.split('#')[0];
-    try {
-      this.setTitle(decodeURIComponent(
-        pdfjsLib.getFilenameFromUrl(url)) || url);
-    } catch (e) {
-      // decodeURIComponent may throw URIError,
-      // fall back to using the unprocessed url in that case
-      this.setTitle(url);
+    var title = getPDFFileNameFromURL(url, '');
+    if (!title) {
+      try {
+        title = decodeURIComponent(pdfjsLib.getFilenameFromUrl(url)) || url;
+      } catch (e) {
+        // decodeURIComponent may throw URIError,
+        // fall back to using the unprocessed url in that case
+        title = url;
+      }
     }
+    this.setTitle(title);
   },
 
   setTitle: function pdfViewSetTitle(title) {

web/ui_utils.js

@@ -368,9 +368,13 @@ function noContextMenuHandler(e) {
 /**
  * Returns the filename or guessed filename from the url (see issue 3455).
  * url {String} The original PDF location.
+ * defaultFilename {string} The value to return if the file name is unknown.
  * @return {String} Guessed PDF file name.
  */
-function getPDFFileNameFromURL(url) {
+function getPDFFileNameFromURL(url, defaultFilename) {
+  if (typeof defaultFilename === 'undefined') {
+    defaultFilename = 'document.pdf';
+  }
   var reURI = /^(?:(?:[^:]+:)?\/\/[^\/]+)?([^?#]*)(\?[^#]*)?(#.*)?$/;
   //            SCHEME        HOST         1.PATH  2.QUERY   3.REF
   // Pattern to get last matching NAME.pdf
@@ -392,7 +396,7 @@ function getPDFFileNameFromURL(url) {
       }
     }
   }
-  return suggestedFilename || 'document.pdf';
+  return suggestedFilename || defaultFilename;
 }
 
 function normalizeWheelEventDelta(evt) {