Add frame count metric to ad tagging benchmark

Adds PageLoad.Clients.Ads.FrameCounts.AdFrames.Total to the set of
metrics recorded in the ad_tagging.cluster_telemetry benchmark. This
will allow for a more direct measurement of frame coverage changes when
filter lists are updated.

Bug: 1036451
Change-Id: I31606e97f45867e6e68f9819f24a3ed1da74eae5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1986426Reviewed-by: John Delaney <johnidel@chromium.org>
Commit-Queue: Alex Turner <alexmt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728251}

tools/perf/contrib/cluster_telemetry/ad_tagging_ct.py

@@ -43,6 +43,7 @@ class AdTaggingClusterTelemetry(perf_benchmark.PerfBenchmark):
         'Ads.ResourceUsage.Size.Network.Subframe.VanillaResource',
         'PageLoad.Clients.Ads.Cpu.AdFrames.Aggregate.TotalUsage',
         'PageLoad.Clients.Ads.Cpu.FullPage.TotalUsage',
+        'PageLoad.Clients.Ads.FrameCounts.AdFrames.Total',
         'PageLoad.Clients.Ads.Resources.Bytes.Ads2',
         'PageLoad.Cpu.TotalUsage',
         'PageLoad.Experimental.Bytes.NetworkIncludingHeaders',