[api-minor] Update telemetry to use 'categorical' histograms.

Firefox telemetry supports using string labels now. Convert our integers
that we used for categories to just use strings.

The upstream work will happen in:
https://bugzilla.mozilla.org/show_bug.cgi?id=1566882

src/core/parser.js

@@ -696,7 +696,7 @@ class Parser {
         return new CCITTFaxStream(stream, maybeLength, params);
       }
       if (name === 'RunLengthDecode' || name === 'RL') {
-        xrefStreamStats[StreamType.RL] = true;
+        xrefStreamStats[StreamType.RLX] = true;
         return new RunLengthStream(stream, maybeLength);
       }
       if (name === 'JBIG2Decode') {

src/shared/util.js

@@ -153,30 +153,30 @@ const AnnotationBorderStyleType = {
 };
 
 const StreamType = {
-  UNKNOWN: 0,
-  FLATE: 1,
-  LZW: 2,
-  DCT: 3,
-  JPX: 4,
-  JBIG: 5,
-  A85: 6,
-  AHX: 7,
-  CCF: 8,
-  RL: 9,
+  UNKNOWN: 'UNKNOWN',
+  FLATE: 'FLATE',
+  LZW: 'LZW',
+  DCT: 'DCT',
+  JPX: 'JPX',
+  JBIG: 'JBIG',
+  A85: 'A85',
+  AHX: 'AHX',
+  CCF: 'CCF',
+  RLX: 'RLX', // PDF short name is 'RL', but telemetry requires three chars.
 };
 
 const FontType = {
-  UNKNOWN: 0,
-  TYPE1: 1,
-  TYPE1C: 2,
-  CIDFONTTYPE0: 3,
-  CIDFONTTYPE0C: 4,
-  TRUETYPE: 5,
-  CIDFONTTYPE2: 6,
-  TYPE3: 7,
-  OPENTYPE: 8,
-  TYPE0: 9,
-  MMTYPE1: 10,
+  UNKNOWN: 'UNKNOWN',
+  TYPE1: 'TYPE1',
+  TYPE1C: 'TYPE1C',
+  CIDFONTTYPE0: 'CIDFONTTYPE0',
+  CIDFONTTYPE0C: 'CIDFONTTYPE0C',
+  TRUETYPE: 'TRUETYPE',
+  CIDFONTTYPE2: 'CIDFONTTYPE2',
+  TYPE3: 'TYPE3',
+  OPENTYPE: 'OPENTYPE',
+  TYPE0: 'TYPE0',
+  MMTYPE1: 'MMTYPE1',
 };
 
 const VerbosityLevel = {

web/app.js

@@ -1137,8 +1137,10 @@ let PDFViewerApplication = {
 
       if (typeof PDFJSDev !== 'undefined' &&
           PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
-        let versionId = String(info.PDFFormatVersion).slice(-1) | 0;
-        let generatorId = 0;
+        // Telemetry labels must be C++ variable friendly.
+        const versionId = `v${info.PDFFormatVersion.replace('.', '_')}`;
+        let generatorId = 'other';
+        // Keep these in sync with mozilla central's Histograms.json.
         const KNOWN_GENERATORS = [
           'acrobat distiller', 'acrobat pdfwriter', 'adobe livecycle',
           'adobe pdf library', 'adobe photoshop', 'ghostscript', 'tcpdf',
@@ -1151,7 +1153,7 @@ let PDFViewerApplication = {
             if (!generator.includes(s)) {
               return false;
             }
-            generatorId = i + 1;
+            generatorId = s.replace(/[ .\-]/g, '_');
             return true;
           }.bind(null, info.Producer.toLowerCase()));
         }