[Audio Focus] Add UMA metrics

Add UMA metrics for tracking audio focus events. There are three
histograms added in total; the first records RequestAudioFocus
calls, the second records AbandonAudioFocus calls and the third
records requested AudioFocusTypes.

In the future we will probably switch these with UKM but UKM is
not available for ARC++ yet.

BUG=883958

Change-Id: I1092b9d1c638a13526687ac77b87d66490e4b89c
Reviewed-on: https://chromium-review.googlesource.com/c/1238871
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597337}

services/media_session/BUILD.gn

@@ -14,6 +14,8 @@ source_set("lib") {
   sources = [
     "audio_focus_manager.cc",
     "audio_focus_manager.h",
+    "audio_focus_manager_metrics_helper.cc",
+    "audio_focus_manager_metrics_helper.h",
     "media_session_service.cc",
     "media_session_service.h",
   ]

services/media_session/audio_focus_manager.cc

@@ -11,6 +11,7 @@
 #include "base/containers/adapters.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
+#include "services/media_session/audio_focus_manager_metrics_helper.h"
 #include "services/media_session/public/cpp/switches.h"
 #include "services/media_session/public/mojom/audio_focus.mojom.h"
 
@@ -38,6 +39,7 @@ class AudioFocusManager::StackRow : public mojom::AudioFocusRequestClient {
            const std::string& source_name)
       : id_(id),
         source_name_(source_name),
+        metrics_helper_(source_name),
         session_(std::move(session)),
         session_info_(std::move(session_info)),
         audio_focus_type_(audio_focus_type),
@@ -50,6 +52,10 @@ class AudioFocusManager::StackRow : public mojom::AudioFocusRequestClient {
     session_.set_connection_error_handler(
         base::BindOnce(&AudioFocusManager::StackRow::OnConnectionError,
                        base::Unretained(this)));
+
+    metrics_helper_.OnRequestAudioFocus(
+        AudioFocusManagerMetricsHelper::AudioFocusRequestSource::kInitial,
+        audio_focus_type);
   }
 
   ~StackRow() override = default;
@@ -73,9 +79,18 @@ class AudioFocusManager::StackRow : public mojom::AudioFocusRequestClient {
 
     owner_->RequestAudioFocusInternal(std::move(row), type,
                                       std::move(callback));
+
+    metrics_helper_.OnRequestAudioFocus(
+        AudioFocusManagerMetricsHelper::AudioFocusRequestSource::kUpdate,
+        audio_focus_type_);
   }
 
-  void AbandonAudioFocus() override { owner_->AbandonAudioFocusInternal(id_); }
+  void AbandonAudioFocus() override {
+    metrics_helper_.OnAbandonAudioFocus(
+        AudioFocusManagerMetricsHelper::AudioFocusAbandonSource::kAPI);
+
+    owner_->AbandonAudioFocusInternal(id_);
+  }
 
   void MediaSessionInfoChanged(mojom::MediaSessionInfoPtr info) override {
     session_info_ = std::move(info);
@@ -110,6 +125,17 @@ class AudioFocusManager::StackRow : public mojom::AudioFocusRequestClient {
 
  private:
   void OnConnectionError() {
+    // Since we have multiple pathways that can call |OnConnectionError| we
+    // should use the |encountered_error_| bit to make sure we abandon focus
+    // just the first time.
+    if (encountered_error_)
+      return;
+    encountered_error_ = true;
+
+    metrics_helper_.OnAbandonAudioFocus(
+        AudioFocusManagerMetricsHelper::AudioFocusAbandonSource::
+            kConnectionError);
+
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::BindOnce(&AudioFocusManager::AbandonAudioFocusInternal,
                                   base::Unretained(owner_), id_));
@@ -118,6 +144,9 @@ class AudioFocusManager::StackRow : public mojom::AudioFocusRequestClient {
   const RequestId id_;
   const std::string source_name_;
 
+  AudioFocusManagerMetricsHelper metrics_helper_;
+  bool encountered_error_ = false;
+
   mojom::MediaSessionPtr session_;
   mojom::MediaSessionInfoPtr session_info_;
   mojom::AudioFocusType audio_focus_type_;

services/media_session/audio_focus_manager_metrics_helper.cc

+// Copyright 2018 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 "services/media_session/audio_focus_manager_metrics_helper.h"
+
+#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_base.h"
+#include "base/strings/string_util.h"
+#include "services/media_session/public/mojom/audio_focus.mojom.h"
+
+namespace media_session {
+
+namespace {
+
+static const char kHistogramPrefix[] = "Media.Session.AudioFocus.";
+static const char kHistogramSeparator[] = ".";
+
+static const char kRequestAudioFocusName[] = "Request";
+static const char kAudioFocusTypeName[] = "Type";
+static const char kAbandonAudioFocusName[] = "Abandon";
+
+static constexpr base::HistogramBase::Sample kHistogramMinimum = 1;
+
+}  // namespace
+
+AudioFocusManagerMetricsHelper::AudioFocusManagerMetricsHelper(
+    const std::string& source_name)
+    : source_name_(source_name),
+      request_source_histogram_(GetHistogram(
+          kRequestAudioFocusName,
+          static_cast<Sample>(AudioFocusRequestSource::kMaxValue))),
+      focus_type_histogram_(
+          GetHistogram(kAudioFocusTypeName,
+                       static_cast<Sample>(AudioFocusType::kMaxValue))),
+      abandon_source_histogram_(GetHistogram(
+          kAbandonAudioFocusName,
+          static_cast<Sample>(AudioFocusAbandonSource::kMaxValue))) {}
+
+AudioFocusManagerMetricsHelper::~AudioFocusManagerMetricsHelper() = default;
+
+void AudioFocusManagerMetricsHelper::OnRequestAudioFocus(
+    AudioFocusManagerMetricsHelper::AudioFocusRequestSource source,
+    mojom::AudioFocusType type) {
+  if (!ShouldRecordMetrics())
+    return;
+
+  request_source_histogram_->Add(static_cast<Sample>(source));
+  focus_type_histogram_->Add(static_cast<Sample>(FromMojoFocusType(type)));
+}
+
+void AudioFocusManagerMetricsHelper::OnAbandonAudioFocus(
+    AudioFocusManagerMetricsHelper::AudioFocusAbandonSource source) {
+  if (!ShouldRecordMetrics())
+    return;
+
+  abandon_source_histogram_->Add(static_cast<Sample>(source));
+}
+
+base::HistogramBase* AudioFocusManagerMetricsHelper::GetHistogram(
+    const char* name,
+    Sample max) const {
+  std::string histogram_name;
+  histogram_name.append(kHistogramPrefix);
+  histogram_name.append(name);
+  histogram_name.append(kHistogramSeparator);
+
+  // This will ensure that |source_name| starts with an upper case letter.
+  for (auto it = source_name_.begin(); it < source_name_.end(); ++it) {
+    if (it == source_name_.begin())
+      histogram_name.push_back(base::ToUpperASCII(*it));
+    else
+      histogram_name.push_back(*it);
+  }
+
+  return base::LinearHistogram::FactoryGet(histogram_name, kHistogramMinimum,
+                                           max, max + 1,
+                                           base::HistogramBase::kNoFlags);
+}
+
+// static
+AudioFocusManagerMetricsHelper::AudioFocusType
+AudioFocusManagerMetricsHelper::FromMojoFocusType(mojom::AudioFocusType type) {
+  switch (type) {
+    case mojom::AudioFocusType::kGain:
+      return AudioFocusType::kGain;
+    case mojom::AudioFocusType::kGainTransientMayDuck:
+      return AudioFocusType::kGainTransientMayDuck;
+    case mojom::AudioFocusType::kGainTransient:
+      return AudioFocusType::kGainTransient;
+  }
+
+  NOTREACHED();
+  return AudioFocusType::kUnknown;
+}
+
+bool AudioFocusManagerMetricsHelper::ShouldRecordMetrics() const {
+  return !source_name_.empty();
+}
+
+}  // namespace media_session

services/media_session/audio_focus_manager_metrics_helper.h

+// Copyright 2018 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.
+
+#ifndef SERVICES_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_METRICS_HELPER_H_
+#define SERVICES_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_METRICS_HELPER_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/metrics/histogram_base.h"
+
+namespace media_session {
+
+namespace mojom {
+enum class AudioFocusType;
+}  // namespace mojom
+
+class AudioFocusManagerMetricsHelper {
+ public:
+  using Sample = base::HistogramBase::Sample;
+
+  AudioFocusManagerMetricsHelper(const std::string& source_name);
+  ~AudioFocusManagerMetricsHelper();
+
+  // This is used for UMA histogram
+  // (Media.Session.AudioFocus.*.RequestAudioFocus). New values should be
+  // appended only and update |kMaxValue|.
+  enum class AudioFocusRequestSource {
+    kUnknown = 0,
+    kInitial = 1,
+    kUpdate = 2,
+    kMaxValue = kUpdate  // Leave at the end.
+  };
+
+  // This is used for UMA histogram
+  // (Media.Session.AudioFocus.*.AbandonAudioFocus). New values should be
+  // appended only and update |kMaxValue|.
+  enum class AudioFocusAbandonSource {
+    kUnknown = 0,
+    kAPI = 1,
+    kConnectionError = 2,
+    kMaxValue = kConnectionError  // Leave at the end.
+  };
+
+  // This is used for UMA histogram
+  // (Media.Session.AudioFocus.*.AudioFocusType). New values should be
+  // appended only and update |kMaxValue|. It should mirror the
+  // media_session::mojom::AudioFocusType enum.
+  enum class AudioFocusType {
+    kUnknown = 0,
+    kGain = 1,
+    kGainTransientMayDuck = 2,
+    kGainTransient = 3,
+    kMaxValue = kGainTransient  // Leave at the end.
+  };
+
+  void OnRequestAudioFocus(AudioFocusRequestSource, mojom::AudioFocusType);
+  void OnAbandonAudioFocus(AudioFocusAbandonSource);
+
+ private:
+  static AudioFocusType FromMojoFocusType(mojom::AudioFocusType);
+
+  base::HistogramBase* GetHistogram(const char* name, Sample max) const;
+
+  bool ShouldRecordMetrics() const;
+
+  const std::string& source_name_;
+
+  base::HistogramBase* const request_source_histogram_;
+  base::HistogramBase* const focus_type_histogram_;
+  base::HistogramBase* const abandon_source_histogram_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioFocusManagerMetricsHelper);
+};
+
+}  // namespace media_session
+
+#endif  // SERVICES_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_METRICS_HELPER_H_

services/media_session/audio_focus_manager_unittest.cc

@@ -11,10 +11,12 @@
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/run_loop.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_command_line.h"
 #include "base/test/scoped_task_environment.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
+#include "services/media_session/audio_focus_manager_metrics_helper.h"
 #include "services/media_session/media_session_service.h"
 #include "services/media_session/public/cpp/switches.h"
 #include "services/media_session/public/cpp/test/audio_focus_test_util.h"
@@ -316,6 +318,17 @@ class AudioFocusManagerTest : public testing::TestWithParam<bool> {
     return requests.back()->source_name.value();
   }
 
+  std::unique_ptr<base::HistogramSamples> GetHistogramSamplesSinceTestStart(
+      const std::string& name) {
+    return histogram_tester_.GetHistogramSamplesSinceCreation(name);
+  }
+
+  int GetAudioFocusHistogramCount() {
+    return histogram_tester_
+        .GetTotalCountsForPrefix("Media.Session.AudioFocus.")
+        .size();
+  }
+
  private:
   int GetCountForType(mojom::AudioFocusType type) {
     const auto audio_focus_requests = GetRequests();
@@ -382,6 +395,7 @@ class AudioFocusManagerTest : public testing::TestWithParam<bool> {
   std::unique_ptr<service_manager::Connector> connector_;
   mojom::AudioFocusManagerPtr audio_focus_ptr_;
   mojom::AudioFocusManagerDebugPtr audio_focus_debug_ptr_;
+  base::HistogramTester histogram_tester_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioFocusManagerTest);
 };
@@ -979,4 +993,102 @@ TEST_P(AudioFocusManagerTest, SourceName_Updated) {
   EXPECT_EQ(kExampleSourceName, GetSourceNameForLastRequest());
 }
 
+TEST_P(AudioFocusManagerTest, RecordUmaMetrics) {
+  EXPECT_EQ(0, GetAudioFocusHistogramCount());
+
+  SetSourceName(kExampleSourceName);
+  MockMediaSession media_session;
+  RequestAudioFocus(&media_session, mojom::AudioFocusType::kGainTransient);
+
+  {
+    std::unique_ptr<base::HistogramSamples> samples(
+        GetHistogramSamplesSinceTestStart(
+            "Media.Session.AudioFocus.Request.Test"));
+    EXPECT_EQ(1, samples->TotalCount());
+    EXPECT_EQ(1, samples->GetCount(static_cast<base::HistogramBase::Sample>(
+                     AudioFocusManagerMetricsHelper::AudioFocusRequestSource::
+                         kInitial)));
+  }
+
+  {
+    std::unique_ptr<base::HistogramSamples> samples(
+        GetHistogramSamplesSinceTestStart(
+            "Media.Session.AudioFocus.Type.Test"));
+    EXPECT_EQ(1, samples->TotalCount());
+    EXPECT_EQ(
+        1,
+        samples->GetCount(static_cast<base::HistogramBase::Sample>(
+            AudioFocusManagerMetricsHelper::AudioFocusType::kGainTransient)));
+  }
+
+  EXPECT_EQ(2, GetAudioFocusHistogramCount());
+
+  RequestAudioFocus(&media_session, mojom::AudioFocusType::kGain);
+
+  {
+    std::unique_ptr<base::HistogramSamples> samples(
+        GetHistogramSamplesSinceTestStart(
+            "Media.Session.AudioFocus.Request.Test"));
+    EXPECT_EQ(2, samples->TotalCount());
+    EXPECT_EQ(
+        1,
+        samples->GetCount(static_cast<base::HistogramBase::Sample>(
+            AudioFocusManagerMetricsHelper::AudioFocusRequestSource::kUpdate)));
+  }
+
+  {
+    std::unique_ptr<base::HistogramSamples> samples(
+        GetHistogramSamplesSinceTestStart(
+            "Media.Session.AudioFocus.Type.Test"));
+    EXPECT_EQ(2, samples->TotalCount());
+    EXPECT_EQ(1, samples->GetCount(static_cast<base::HistogramBase::Sample>(
+                     AudioFocusManagerMetricsHelper::AudioFocusType::kGain)));
+  }
+
+  EXPECT_EQ(2, GetAudioFocusHistogramCount());
+
+  AbandonAudioFocus(&media_session);
+
+  {
+    std::unique_ptr<base::HistogramSamples> samples(
+        GetHistogramSamplesSinceTestStart(
+            "Media.Session.AudioFocus.Abandon.Test"));
+    EXPECT_EQ(1, samples->TotalCount());
+    EXPECT_EQ(
+        1, samples->GetCount(static_cast<base::HistogramBase::Sample>(
+               AudioFocusManagerMetricsHelper::AudioFocusAbandonSource::kAPI)));
+  }
+
+  EXPECT_EQ(3, GetAudioFocusHistogramCount());
+}
+
+TEST_P(AudioFocusManagerTest, RecordUmaMetrics_ConnectionError) {
+  SetSourceName(kExampleSourceName);
+
+  {
+    MockMediaSession media_session;
+    RequestAudioFocus(&media_session, mojom::AudioFocusType::kGain);
+  }
+
+  MockMediaSession media_session;
+  RequestAudioFocus(&media_session, mojom::AudioFocusType::kGain);
+
+  {
+    std::unique_ptr<base::HistogramSamples> samples(
+        GetHistogramSamplesSinceTestStart(
+            "Media.Session.AudioFocus.Abandon.Test"));
+    EXPECT_EQ(1, samples->TotalCount());
+    EXPECT_EQ(1, samples->GetCount(static_cast<base::HistogramBase::Sample>(
+                     AudioFocusManagerMetricsHelper::AudioFocusAbandonSource::
+                         kConnectionError)));
+  }
+}
+
+TEST_P(AudioFocusManagerTest, RecordUmaMetrics_NoSourceName) {
+  MockMediaSession media_session;
+  RequestAudioFocus(&media_session, mojom::AudioFocusType::kGain);
+
+  EXPECT_EQ(0, GetAudioFocusHistogramCount());
+}
+
 }  // namespace media_session

tools/metrics/histograms/enums.xml

@@ -2147,6 +2147,25 @@ uploading your change for review.  These are checked by presubmit scripts.
   <int value="54" label="Sub mute"/>
 </enum>
 
+<enum name="AudioFocusAbandonSource">
+  <int value="0" label="Unknown"/>
+  <int value="1" label="API"/>
+  <int value="2" label="Connection Error"/>
+</enum>
+
+<enum name="AudioFocusRequestSource">
+  <int value="0" label="Unknown"/>
+  <int value="1" label="Initial request"/>
+  <int value="2" label="Update existing request"/>
+</enum>
+
+<enum name="AudioFocusType">
+  <int value="0" label="Unknown"/>
+  <int value="1" label="Gain"/>
+  <int value="2" label="Gain transient may duck"/>
+  <int value="3" label="Gain transient"/>
+</enum>
+
 <enum name="AudioFramesPerBuffer">
   <obsolete>
     Removed from code Sep 2014.

tools/metrics/histograms/histograms.xml

@@ -44432,6 +44432,39 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="Media.Session.AudioFocus.Abandon"
+    enum="AudioFocusAbandonSource" expires_after="2019-10-03">
+  <owner>beccahughes@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    The number of times a media session abandon audio focus and where the
+    abandon audio focus call originated from. This is recorded every time a
+    media session abandons audio focus because it has stopped playing.
+  </summary>
+</histogram>
+
+<histogram name="Media.Session.AudioFocus.Request"
+    enum="AudioFocusRequestSource" expires_after="2019-10-03">
+  <owner>beccahughes@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    The number of times a media session requested audio focus and where that
+    focus request originated from. This is recorded every time a media session
+    requests audio focus because it wants to start playing.
+  </summary>
+</histogram>
+
+<histogram name="Media.Session.AudioFocus.Type" enum="AudioFocusType">
+  <owner>beccahughes@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    The number of times a media session requested audio focus for a specific
+    audio focus type. This is recorded every time a media session requests a new
+    audio focus type. This may be because the session has started playing or the
+    type of media being played has changed.
+  </summary>
+</histogram>
+
 <histogram name="Media.Session.Pause" enum="MediaSessionActionSource">
   <owner>avayvod@chromium.org</owner>
   <owner>mlamouri@chromium.org</owner>
@@ -125697,6 +125730,14 @@ uploading your change for review.
   <affected-histogram name="MediaRouter.Cast.App.Availability"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="MediaSessionSource" separator=".">
+  <suffix name="Arc" label="ARC++ app"/>
+  <suffix name="Web" label="Website"/>
+  <affected-histogram name="Media.Session.AudioFocus.Abandon"/>
+  <affected-histogram name="Media.Session.AudioFocus.Request"/>
+  <affected-histogram name="Media.Session.AudioFocus.Type"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="MediaStreamAndDecoderType" separator=".">
   <suffix name="Audio.HW" label="Platform audio decoder"/>
   <suffix name="Audio.SW" label="Software audio decoder"/>