Fix various Rendering Core UMA metrics

The Blink.ForcedStyleAndLayout.UpdateTime metric has too many samples
and sometimes overflows the sample counter in a 30 minute period. So
randomly choose to sample with 1/100 probability.

The Blink.Compositing.LayerPromotionCount.IndirectComposited UMA has
a bigger range than the histogram, so increase the max value and the
number of buckets.

Bug: 950600,950540
Change-Id: I8bd9bf30ed73c4ef61742ab4664c6eb4e5c8ae18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613748
Auto-Submit: Stephen Chenney <schenney@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660922}

third_party/blink/renderer/core/frame/local_frame_ukm_aggregator.cc

@@ -139,8 +139,14 @@ void LocalFrameUkmAggregator::RecordSample(size_t metric_index,
   auto& record = absolute_metric_records_[metric_index];
   record.interval_duration += duration;
   // Record the UMA
-  if (record.uma_counter)
+  // ForcedStyleAndLayout happen so frequently on some pages that we overflow
+  // the signed 32 counter for number of events in a 30 minute period. So
+  // randomly record with probability 1/100.
+  if (record.uma_counter &&
+      (metric_index != static_cast<MetricId>(kForcedStyleAndLayout) ||
+       base::RandInt(0, 99) == 0)) {
     record.uma_counter->CountMicroseconds(duration);
+  }
 
   // Only record ratios when inside a main frame.
   if (in_main_frame_update_) {

third_party/blink/renderer/core/paint/compositing/paint_layer_compositor.cc

@@ -183,7 +183,7 @@ void PaintLayerCompositor::UpdateIfNeededRecursive(
       compositing_reasons_stats.assumed_overlap_layers, 1, 1000, 5);
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "Blink.Compositing.LayerPromotionCount.IndirectComposited",
-      compositing_reasons_stats.indirect_composited_layers, 1, 1000, 5);
+      compositing_reasons_stats.indirect_composited_layers, 1, 10000, 10);
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "Blink.Compositing.LayerPromotionCount.TotalComposited",
       compositing_reasons_stats.total_composited_layers, 1, 1000, 10);