[On-device adaptive brightness] Log UserAdjustment counts to UMA.

We split user adjustments into two types: with or without prior model
adjustments.

Bug: 881215
Change-Id: I34c6084ef96cfcf81f97c0825951a340934c4557
Reviewed-on: https://chromium-review.googlesource.com/c/1312179
Commit-Queue: Jia Meng <jiameng@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605250}

chrome/browser/chromeos/power/auto_screen_brightness/adapter.cc

@@ -8,6 +8,7 @@
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial_params.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/time/default_tick_clock.h"
 #include "chrome/browser/chromeos/power/auto_screen_brightness/utils.h"
 #include "chrome/browser/profiles/profile.h"
@@ -88,6 +89,11 @@ void Adapter::OnUserBrightnessChanged(double old_brightness_percent,
                                       double new_brightness_percent) {}
 
 void Adapter::OnUserBrightnessChangeRequested() {
+  UMA_HISTOGRAM_ENUMERATION("AutoScreenBrightness.UserAdjustment",
+                            latest_brightness_change_time_.is_null()
+                                ? UserAdjustment::kNoPriorModelAdjustment
+                                : UserAdjustment::kWithPriorModelAdjustment);
+
   // This will disable |adapter_status_| so that the model will not make any
   // brightness adjustment.
   adapter_status_ = Status::kDisabled;

chrome/browser/chromeos/power/auto_screen_brightness/adapter.h

@@ -47,6 +47,14 @@ class Adapter : public AlsReader::Observer,
     kMaxValue = kLatest
   };
 
+  // These values are persisted to logs. Entries should not be renumbered and
+  // numeric values should never be reused.
+  enum class UserAdjustment {
+    kNoPriorModelAdjustment = 0,
+    kWithPriorModelAdjustment = 1,
+    kMaxValue = kWithPriorModelAdjustment
+  };
+
   // TODO(jiameng): we currently use past 2 seconds of ambient values to
   // calculate average ambient when we predict optimal brightness. This is
   // shorter than the duration used for training data (10 seconds), because it's

chrome/browser/chromeos/power/auto_screen_brightness/adapter_unittest.cc

@@ -7,6 +7,7 @@
 #include "ash/public/cpp/ash_pref_names.h"
 #include "base/memory/ptr_util.h"
 #include "base/task/task_scheduler/task_scheduler.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/test/scoped_task_environment.h"
 #include "base/threading/sequenced_task_runner_handle.h"
@@ -34,6 +35,14 @@ namespace auto_screen_brightness {
 
 namespace {
 
+using SamplesCounts = std::vector<
+    std::pair<base::HistogramBase::Sample, base::HistogramBase::Count>>;
+
+constexpr auto kNoPriorModelAdjustment =
+    static_cast<int>(Adapter::UserAdjustment::kNoPriorModelAdjustment);
+constexpr auto kWithPriorModelAdjustment =
+    static_cast<int>(Adapter::UserAdjustment::kWithPriorModelAdjustment);
+
 // Testing modeller.
 class FakeModeller : public Modeller {
  public:
@@ -196,10 +205,25 @@ class AdapterTest : public testing::Test {
     scoped_task_environment_.RunUntilIdle();
   }
 
+  void VerifyHistogramCounts(
+      const std::map<std::string, SamplesCounts>& expected_values) {
+    for (const auto& histogram_samples : expected_values) {
+      const std::string& histogram_name = histogram_samples.first;
+      const SamplesCounts& samples_counts = histogram_samples.second;
+      for (const auto& sample_count : samples_counts) {
+        const base::HistogramBase::Sample& sample = sample_count.first;
+        const base::HistogramBase::Count& count = sample_count.second;
+        histogram_tester_.ExpectUniqueSample(histogram_name, sample, count);
+      }
+    }
+  }
+
  protected:
   base::test::ScopedTaskEnvironment scoped_task_environment_;
   content::TestBrowserThreadBundle thread_bundle_;
 
+  base::HistogramTester histogram_tester_;
+
   TestObserver test_observer_;
 
   base::ScopedTempDir temp_dir_;
@@ -385,6 +409,44 @@ TEST_F(AdapterTest, SequenceOfBrightnessUpdatesWithDefaultParams) {
   fake_brightness_monitor_.ReportUserBrightnessChangeRequested();
   scoped_task_environment_.RunUntilIdle();
   EXPECT_EQ(adapter_->GetStatusForTesting(), Adapter::Status::kDisabled);
+
+  VerifyHistogramCounts({{"AutoScreenBrightness.UserAdjustment",
+                          {{kWithPriorModelAdjustment, 1}}}});
+
+  // Another user manual adjustment came in.
+  fake_brightness_monitor_.ReportUserBrightnessChangeRequested();
+  scoped_task_environment_.RunUntilIdle();
+  EXPECT_EQ(adapter_->GetStatusForTesting(), Adapter::Status::kDisabled);
+
+  VerifyHistogramCounts({{"AutoScreenBrightness.UserAdjustment",
+                          {{kWithPriorModelAdjustment, 2}}}});
+}
+
+TEST_F(AdapterTest, UserBrightnessRequestBeforeAnyModelUpdate) {
+  Init(AlsReader::AlsInitStatus::kSuccess, BrightnessMonitor::Status::kSuccess,
+       global_curve_, personal_curve_, default_params_);
+
+  EXPECT_EQ(adapter_->GetStatusForTesting(), Adapter::Status::kSuccess);
+  EXPECT_TRUE(adapter_->GetGlobalCurveForTesting());
+  EXPECT_EQ(*adapter_->GetGlobalCurveForTesting(), *global_curve_);
+  EXPECT_TRUE(adapter_->GetPersonalCurveForTesting());
+  EXPECT_EQ(*adapter_->GetPersonalCurveForTesting(), *personal_curve_);
+
+  // Adapter is disabled after a user manual adjustment.
+  fake_brightness_monitor_.ReportUserBrightnessChangeRequested();
+  scoped_task_environment_.RunUntilIdle();
+  EXPECT_EQ(adapter_->GetStatusForTesting(), Adapter::Status::kDisabled);
+
+  VerifyHistogramCounts({{"AutoScreenBrightness.UserAdjustment",
+                          {{kNoPriorModelAdjustment, 1}}}});
+
+  // Another user manual adjustment came in.
+  fake_brightness_monitor_.ReportUserBrightnessChangeRequested();
+  scoped_task_environment_.RunUntilIdle();
+  EXPECT_EQ(adapter_->GetStatusForTesting(), Adapter::Status::kDisabled);
+
+  VerifyHistogramCounts({{"AutoScreenBrightness.UserAdjustment",
+                          {{kNoPriorModelAdjustment, 2}}}});
 }
 
 TEST_F(AdapterTest, BrightnessLuxThresholds) {

tools/metrics/histograms/enums.xml

@@ -3243,6 +3243,11 @@ uploading your change for review.  These are checked by presubmit scripts.
   <int value="2" label="dual source"/>
 </enum>
 
+<enum name="AutoScreenBrightnessUserAdjustment">
+  <int value="0" label="NoPriorModelAdjustment"/>
+  <int value="1" label="WithPriorModelAdjustment"/>
+</enum>
+
 <enum name="AutoSigninFirstRun">
   <int value="0" label="No action"/>
   <int value="1" label="Turn off"/>

tools/metrics/histograms/histograms.xml

@@ -8140,6 +8140,12 @@ uploading your change for review.
   <summary>Whether the user changed autofilled field.</summary>
 </histogram>
 
+<histogram name="AutoScreenBrightness.UserAdjustment"
+    enum="AutoScreenBrightnessUserAdjustment">
+  <owner>jiameng@chromium.org</owner>
+  <summary>Type of user manual screen brightness adjustment.</summary>
+</histogram>
+
 <histogram base="true" name="BackgroundFetch.EventDispatchFailure.Dispatch"
     enum="ServiceWorkerStatusCode">
 <!-- Name completed by histogram_suffixes name="BackgroundFetchEvents" -->