chrome/browser/optimization_guide/browser_test_util.cc

// Copyright 2021 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/optimization_guide/browser_test_util.h"

#include "base/run_loop.h"
#include "base/task/thread_pool/thread_pool_instance.h"
#include "base/test/metrics/histogram_tester.h"
#include "components/metrics/content/subprocess_metrics_provider.h"
#include "content/public/test/browser_test_utils.h"

namespace optimization_guide {

namespace {

// Fetch and calculate the total number of samples from all the bins for
// |histogram_name|. Note: from some browertests run (such as chromeos) there
// might be two profiles created, and this will return the total sample count
// across profiles.
int GetTotalHistogramSamples(const base::HistogramTester* histogram_tester,
                             const std::string& histogram_name) {
  std::vector<base::Bucket> buckets =
      histogram_tester->GetAllSamples(histogram_name);
  int total = 0;
  for (const auto& bucket : buckets)
    total += bucket.count;

  return total;
}

}  // namespace

int RetryForHistogramUntilCountReached(
    const base::HistogramTester* histogram_tester,
    const std::string& histogram_name,
    int count) {
  while (true) {
    base::ThreadPoolInstance::Get()->FlushForTesting();
    base::RunLoop().RunUntilIdle();

    content::FetchHistogramsFromChildProcesses();
    metrics::SubprocessMetricsProvider::MergeHistogramDeltasForTesting();

    int total = GetTotalHistogramSamples(histogram_tester, histogram_name);
    if (total >= count)
      return total;
  }
}

}  // namespace optimization_guide