Add a TBMv2 webrtc_rendering_metric.

tracing/tracing/base/utils_test.html

Index: tracing/tracing/base/utils_test.html
diff --git a/tracing/tracing/base/utils_test.html b/tracing/tracing/base/utils_test.html
index 8e7c91a7fceb57231f766e86c90dc45b4e7ccc64..c83076829e6088e6ddf2f3fc318428850a1093b3 100644
--- a/tracing/tracing/base/utils_test.html
+++ b/tracing/tracing/base/utils_test.html
@@ -29,5 +29,43 @@ tr.b.unittest.testSuite(function() {
   test('formatDate', function() {
     assert.strictEqual(tr.b.formatDate(new Date(0)), '1970-01-01 00:00:00');
   });
+
+  test('runLengthEncoding', function() {
+    assert.deepEqual(tr.b.runLengthEncoding([]), []);
+    assert.deepEqual(
+        tr.b.runLengthEncoding([1, 1]),
+        [{
+          value: 1,
+          count: 2,
+        }]);
+    assert.deepEqual(
+        tr.b.runLengthEncoding([1, 2]),
+        [{
+          value: 1,
+          count: 1,
+        },
+        {
+          value: 2,
+          count: 1,
+        }]);
+    assert.deepEqual(
+        tr.b.runLengthEncoding([1, 1, 2, 2, 2, 3, 4, 4]),
+        [{
+          value: 1,
+          count: 2,
+        },
+        {
+          value: 2,
+          count: 3,
+        },
+        {
+          value: 3,
+          count: 1,
+        },
+        {
+          value: 4,
+          count: 2,
+        }]);
+  });
 });
 </script>