Bug 1306624 - Add telemetry probes to count how many times a user requests to print a document. r=mconley, data-review=liuche

toolkit/components/telemetry/Histograms.json

@@ -6289,6 +6289,15 @@
      "releaseChannelCollection": "opt-out",
      "description": "A counter incremented every time the simplified mode is unavailable on print preview."
    },
+  "PRINT_DIALOG_OPENED_COUNT": {
+    "alert_emails": ["carnold@mozilla.org"],
+    "bug_numbers": [1306624],
+    "expires_in_version": "56",
+    "kind": "count",
+    "keyed": true,
+    "releaseChannelCollection": "opt-out",
+    "description": "A counter incremented every time the user opens print dialog."
+  },
   "PRINT_COUNT": {
      "alert_emails": ["carnold@mozilla.org"],
      "bug_numbers": [1287587],

toolkit/content/browser-content.js

@@ -647,17 +647,23 @@ var Printing = {
     try {
       let print = contentWindow.QueryInterface(Ci.nsIInterfaceRequestor)
                                .getInterface(Ci.nsIWebBrowserPrint);
+
+      if (print.doingPrintPreview) {
+        this.logKeyedTelemetry("PRINT_DIALOG_OPENED_COUNT", "FROM_PREVIEW");
+      } else {
+        this.logKeyedTelemetry("PRINT_DIALOG_OPENED_COUNT", "FROM_PAGE");
+      }
+
       print.print(printSettings, null);
 
-      let histogram = Services.telemetry.getKeyedHistogramById("PRINT_COUNT");
       if (print.doingPrintPreview) {
         if (simplifiedMode) {
-          histogram.add("SIMPLIFIED");
+          this.logKeyedTelemetry("PRINT_COUNT", "SIMPLIFIED");
         } else {
-          histogram.add("WITH_PREVIEW");
+          this.logKeyedTelemetry("PRINT_COUNT", "WITH_PREVIEW");
         }
       } else {
-        histogram.add("WITHOUT_PREVIEW");
+        this.logKeyedTelemetry("PRINT_COUNT", "WITHOUT_PREVIEW");
       }
     } catch (e) {
       // Pressing cancel is expressed as an NS_ERROR_ABORT return value,
@@ -683,6 +689,11 @@ var Printing = {
     }
   },
 
+  logKeyedTelemetry(id, key) {
+    let histogram = Services.telemetry.getKeyedHistogramById(id);
+    histogram.add(key);
+  },
+
   updatePageCount() {
     let numPages = docShell.printPreview.printPreviewNumPages;
     sendAsyncMessage("Printing:Preview:UpdatePageCount", {