Revert of Add support for single sample metrics.

base/metrics/single_sample_metrics.cc

Index: base/metrics/single_sample_metrics.cc
diff --git a/base/metrics/single_sample_metrics.cc b/base/metrics/single_sample_metrics.cc
deleted file mode 100644
index 66fdb14bda5afc7d61da10ee77f1713afd18a1e6..0000000000000000000000000000000000000000
--- a/base/metrics/single_sample_metrics.cc
+++ /dev/null
@@ -1,77 +0,0 @@
-// Copyright 2017 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 "base/metrics/single_sample_metrics.h"
-
-#include "base/memory/ptr_util.h"
-#include "base/metrics/histogram.h"
-
-namespace base {
-
-static SingleSampleMetricsFactory* g_factory = nullptr;
-
-// static
-SingleSampleMetricsFactory* SingleSampleMetricsFactory::Get() {
-  if (!g_factory)
-    g_factory = new DefaultSingleSampleMetricsFactory();
-
-  return g_factory;
-}
-
-// static
-void SingleSampleMetricsFactory::SetFactory(
-    std::unique_ptr<SingleSampleMetricsFactory> factory) {
-  DCHECK(!g_factory);
-  g_factory = factory.release();
-}
-
-// static
-void SingleSampleMetricsFactory::DeleteFactoryForTesting() {
-  DCHECK(g_factory);
-  delete g_factory;
-  g_factory = nullptr;
-}
-
-std::unique_ptr<SingleSampleMetric>
-DefaultSingleSampleMetricsFactory::CreateCustomCountsMetric(
-    const std::string& histogram_name,
-    HistogramBase::Sample min,
-    HistogramBase::Sample max,
-    uint32_t bucket_count) {
-  return MakeUnique<DefaultSingleSampleMetric>(
-      histogram_name, min, max, bucket_count,
-      HistogramBase::kUmaTargetedHistogramFlag);
-}
-
-DefaultSingleSampleMetric::DefaultSingleSampleMetric(
-    const std::string& histogram_name,
-    HistogramBase::Sample min,
-    HistogramBase::Sample max,
-    uint32_t bucket_count,
-    int32_t flags)
-    : histogram_(Histogram::FactoryGet(histogram_name,
-                                       min,
-                                       max,
-                                       bucket_count,
-                                       flags)) {
-  // Bad construction parameters may lead to |histogram_| being null; DCHECK to
-  // find accidental errors in production. We must still handle the nullptr in
-  // destruction though since this construction may come from another untrusted
-  // process.
-  DCHECK(histogram_);
-}
-
-DefaultSingleSampleMetric::~DefaultSingleSampleMetric() {
-  // |histogram_| may be nullptr if bad construction parameters are given.
-  if (sample_ < 0 || !histogram_)
-    return;
-  histogram_->Add(sample_);
-}
-
-void DefaultSingleSampleMetric::SetSample(HistogramBase::Sample sample) {
-  DCHECK_GE(sample, 0);
-  sample_ = sample;
-}
-
-}  // namespace base