Bug 1736864, add extra telemetry flag to indicate if the pdf viewer is opening an attachment, r=Gijs

Note that this doesn't ever trigger currently as pdf files loaded as attachments always get downloaded go through the external helper service

Differential Revision: https://phabricator.services.mozilla.com/D130098

toolkit/components/pdfjs/content/PdfJsTelemetry.jsm

@@ -21,8 +21,11 @@ var EXPORTED_SYMBOLS = ["PdfJsTelemetry"];
 const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 var PdfJsTelemetry = {
-  onViewerIsUsed() {
+  onViewerIsUsed(isAttachment) {
     Services.telemetry.scalarAdd("pdf.viewer.used", 1);
+    if (isAttachment) {
+      Services.telemetry.scalarAdd("pdf.viewer.is_attachment", 1);
+    }
   },
   onFallbackError(featureId) {
     let histogram = Services.telemetry.getHistogramById(

toolkit/components/pdfjs/content/PdfStreamConverter.jsm

@@ -1209,8 +1209,10 @@ PdfStreamConverter.prototype = {
 
     aRequest.QueryInterface(Ci.nsIWritablePropertyBag);
 
+    var contentDisposition = aRequest.DISPOSITION_INLINE;
     var contentDispositionFilename;
     try {
+      contentDisposition = aRequest.contentDisposition;
       contentDispositionFilename = aRequest.contentDispositionFilename;
     } catch (e) {}
 
@@ -1229,7 +1231,9 @@ PdfStreamConverter.prototype = {
       aRequest.setResponseHeader("Refresh", "", false);
     }
 
-    PdfJsTelemetry.onViewerIsUsed();
+    PdfJsTelemetry.onViewerIsUsed(
+      contentDisposition == aRequest.DISPOSITION_ATTACHMENT
+    );
     PdfJsTelemetry.onDocumentSize(aRequest.contentLength);
 
     // Creating storage for PDF data

toolkit/components/telemetry/Scalars.yaml

@@ -4182,6 +4182,21 @@ pdf.viewer:
     record_in_processes:
       - 'main'
       - 'content'
+  is_attachment:
+    bug_numbers:
+      - 1736864
+    description: >
+      How many times a PDF that sends Content-Disposition: attachment is opened.
+    expires: "100"
+    kind: uint
+    notification_emails:
+      - rtestard@mozilla.com
+    release_channel_collection: opt-out
+    products:
+      - 'firefox'
+    record_in_processes:
+      - 'main'
+      - 'content'
   fallback_shown:
     bug_numbers:
       - 1566882