Ad metrics: Remove PageLoad.Clients.Ads...PercentNetwork2 histograms.

This makes the histogram obsolete and removes the lines that record
and test it.

Bug: 1135300
Change-Id: I12c61700e32d44875a0fa96ec41bf62eff9aeb2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2472523Reviewed-by: John Delaney <johnidel@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Cammie Smith Barnes <cammie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817713}

chrome/browser/page_load_metrics/observers/ad_metrics/ads_page_load_metrics_observer.cc

@@ -1023,13 +1023,6 @@ void AdsPageLoadMetricsObserver::RecordAggregateHistogramsForAdTagging(
   ADS_HISTOGRAM("Bytes.AdFrames.Aggregate.Network", PAGE_BYTES_HISTOGRAM,
                 visibility, aggregate_ad_info.network_bytes);
 
-  if (aggregate_ad_info.bytes) {
-    ADS_HISTOGRAM(
-        "Bytes.AdFrames.Aggregate.PercentNetwork2", UMA_HISTOGRAM_PERCENTAGE,
-        visibility,
-        aggregate_ad_info.network_bytes * 100 / aggregate_ad_info.bytes);
-  }
-
   if (memory_request_) {
     ADS_HISTOGRAM("Memory.Aggregate.Max", PAGE_BYTES_HISTOGRAM, visibility,
                   aggregate_ad_info.v8_max_memory_bytes);
@@ -1153,12 +1146,6 @@ void AdsPageLoadMetricsObserver::RecordPerFrameHistogramsForAdTagging(
                   visibility, ad_frame_data.bytes());
     ADS_HISTOGRAM("Bytes.AdFrames.PerFrame.Network", PAGE_BYTES_HISTOGRAM,
                   visibility, ad_frame_data.network_bytes());
-    if (ad_frame_data.bytes() > 0) {
-      ADS_HISTOGRAM(
-          "Bytes.AdFrames.PerFrame.PercentNetwork2", UMA_HISTOGRAM_PERCENTAGE,
-          visibility,
-          ad_frame_data.network_bytes() * 100 / ad_frame_data.bytes());
-    }
     if (memory_request_) {
       ADS_HISTOGRAM("Memory.PerFrame.Max", PAGE_BYTES_HISTOGRAM, visibility,
                     ad_frame_data.v8_max_memory_bytes_used());

chrome/browser/page_load_metrics/observers/ad_metrics/ads_page_load_metrics_observer_unittest.cc

@@ -312,12 +312,6 @@ void TestHistograms(const base::HistogramTester& histograms,
         SuffixedHistogram("Bytes.AdFrames.PerFrame.Network"),
         network_bytes_and_count.first, network_bytes_and_count.second);
   }
-  for (const auto& percent_network_and_count :
-       frames_with_percent_network_count) {
-    histograms.ExpectBucketCount(
-        SuffixedHistogram("Bytes.AdFrames.PerFrame.PercentNetwork2"),
-        percent_network_and_count.first, percent_network_and_count.second);
-  }
 
   histograms.ExpectUniqueSample(
       SuffixedHistogram("Bytes.AdFrames.Aggregate.Total2"), total_ad_kb, 1);
@@ -339,11 +333,6 @@ void TestHistograms(const base::HistogramTester& histograms,
             (total_ad_kb + non_ad_cached_kb + non_ad_uncached_kb),
         1);
   }
-  if (total_ad_kb > 0) {
-    histograms.ExpectUniqueSample(
-        SuffixedHistogram("Bytes.AdFrames.Aggregate.PercentNetwork2"),
-        ((total_ad_uncached_kb * 100) / total_ad_kb), 1);
-  }
   if (total_ad_uncached_kb + non_ad_uncached_kb > 0) {
     histograms.ExpectUniqueSample(
         SuffixedHistogram("Bytes.FullPage.Network.PercentAdFrames"),

tools/metrics/histograms/histograms_xml/histogram_suffixes_list.xml

@@ -523,7 +523,11 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
     </obsolete>
   </suffix>
   <suffix name="PercentNetwork2"
-      label="The percentage of bytes that were loaded over the network."/>
+      label="The percentage of bytes that were loaded over the network.">
+    <obsolete>
+      Removed 10/2020.
+    </obsolete>
+  </suffix>
   <affected-histogram name="PageLoad.Clients.Ads.Bytes.AdFrames.Aggregate"/>
   <affected-histogram name="PageLoad.Clients.Ads.Bytes.AdFrames.PerFrame"/>
   <affected-histogram