Revert of Add support for single sample metrics.

components/metrics/single_sample_metrics.cc

-// 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 "components/metrics/single_sample_metrics.h"
-
-#include <utility>
-
-#include "base/memory/ptr_util.h"
-#include "base/metrics/single_sample_metrics.h"
-#include "base/threading/thread_checker.h"
-#include "components/metrics/single_sample_metrics_factory_impl.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
-
-namespace metrics {
-
-namespace {
-
-class MojoSingleSampleMetric : public mojom::SingleSampleMetric {
- public:
-  MojoSingleSampleMetric(const std::string& histogram_name,
-                         base::HistogramBase::Sample min,
-                         base::HistogramBase::Sample max,
-                         uint32_t bucket_count,
-                         int32_t flags)
-      : metric_(histogram_name, min, max, bucket_count, flags) {}
-  ~MojoSingleSampleMetric() override {}
-
- private:
-  // mojom::SingleSampleMetric:
-  void SetSample(base::HistogramBase::Sample sample) override {
-    metric_.SetSample(sample);
-  }
-
-  base::DefaultSingleSampleMetric metric_;
-
-  DISALLOW_COPY_AND_ASSIGN(MojoSingleSampleMetric);
-};
-
-class MojoSingleSampleMetricsProvider
-    : public mojom::SingleSampleMetricsProvider {
- public:
-  MojoSingleSampleMetricsProvider() {}
-  ~MojoSingleSampleMetricsProvider() override {
-    DCHECK(thread_checker_.CalledOnValidThread());
-  }
-
- private:
-  // mojom::SingleSampleMetricsProvider:
-  void AcquireSingleSampleMetric(
-      const std::string& histogram_name,
-      base::HistogramBase::Sample min,
-      base::HistogramBase::Sample max,
-      uint32_t bucket_count,
-      int32_t flags,
-      mojom::SingleSampleMetricRequest request) override {
-    DCHECK(thread_checker_.CalledOnValidThread());
-    mojo::MakeStrongBinding(base::MakeUnique<MojoSingleSampleMetric>(
-                                histogram_name, min, max, bucket_count, flags),
-                            std::move(request));
-  }
-
-  // Providers must be created, used on, and destroyed on the same thread.
-  base::ThreadChecker thread_checker_;
-
-  DISALLOW_COPY_AND_ASSIGN(MojoSingleSampleMetricsProvider);
-};
-
-}  // namespace
-
-// static
-void InitializeSingleSampleMetricsFactory(CreateProviderCB create_provider_cb) {
-  base::SingleSampleMetricsFactory::SetFactory(
-      base::MakeUnique<SingleSampleMetricsFactoryImpl>(
-          std::move(create_provider_cb)));
-}
-
-// static
-void CreateSingleSampleMetricsProvider(
-    const service_manager::BindSourceInfo& source_info,
-    mojom::SingleSampleMetricsProviderRequest request) {
-  mojo::MakeStrongBinding(base::MakeUnique<MojoSingleSampleMetricsProvider>(),
-                          std::move(request));
-}
-
-}  // namespace metrics