Stub out Firefox addon Telemetry wrapper

We are planning to remove the addon histogram APIs from Firefox
Telemetry.
The easy solution here is to just stub out all calls that use them.

extensions/firefox/content/PdfJsTelemetry-addon.jsm

@@ -19,70 +19,27 @@
 
 this.EXPORTED_SYMBOLS = ["PdfJsTelemetry"];
 
-const Cu = Components.utils;
-Cu.import("resource://gre/modules/Services.jsm");
-
-const ADDON_ID = "uriloader@pdf.js";
-
-var Telemetry = Services.telemetry;
-var registerAddonHistogram = Telemetry.registerAddonHistogram;
-
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_USED", Telemetry.HISTOGRAM_BOOLEAN, 1, 2, 3);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_FALLBACK_SHOWN", Telemetry.HISTOGRAM_BOOLEAN, 1, 2, 3);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_DOCUMENT_VERSION", Telemetry.HISTOGRAM_LINEAR, 1, 10, 11);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_DOCUMENT_GENERATOR", Telemetry.HISTOGRAM_LINEAR, 1, 25, 26);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_DOCUMENT_SIZE_KB", Telemetry.HISTOGRAM_EXPONENTIAL, 2, 64 * 1024, 20);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_EMBED", Telemetry.HISTOGRAM_BOOLEAN, 1, 2, 3);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_FONT_TYPES", Telemetry.HISTOGRAM_LINEAR, 1, 19, 20);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_FORM", Telemetry.HISTOGRAM_BOOLEAN, 1, 2, 3);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_PRINT", Telemetry.HISTOGRAM_BOOLEAN, 1, 2, 3);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_STREAM_TYPES", Telemetry.HISTOGRAM_LINEAR, 1, 19, 20);
-registerAddonHistogram(ADDON_ID, "PDF_VIEWER_TIME_TO_VIEW_MS", Telemetry.HISTOGRAM_EXPONENTIAL, 1, 10000, 50);
-
-
 this.PdfJsTelemetry = {
   onViewerIsUsed() {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_USED");
-    histogram.add(true);
   },
   onFallback() {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_FALLBACK_SHOWN");
-    histogram.add(true);
   },
   onDocumentSize(size) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_DOCUMENT_SIZE_KB");
-    histogram.add(size / 1024);
   },
   onDocumentVersion(versionId) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_DOCUMENT_VERSION");
-    histogram.add(versionId);
   },
   onDocumentGenerator(generatorId) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_DOCUMENT_GENERATOR");
-    histogram.add(generatorId);
   },
   onEmbed(isObject) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_EMBED");
-    histogram.add(isObject);
   },
   onFontType(fontTypeId) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_FONT_TYPES");
-    histogram.add(fontTypeId);
   },
   onForm(isAcroform) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_FORM");
-    histogram.add(isAcroform);
   },
   onPrint() {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_PRINT");
-    histogram.add(true);
   },
   onStreamType(streamTypeId) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_STREAM_TYPES");
-    histogram.add(streamTypeId);
   },
   onTimeToView(ms) {
-    let histogram = Telemetry.getAddonHistogram(ADDON_ID, "PDF_VIEWER_TIME_TO_VIEW_MS");
-    histogram.add(ms);
   }
 };