cros: Add histogram for tracking desk lifetime.

This CL adds a histogram for tracking desk lifetime. Desks now store
their creation time and emits their lifetime as a record when they are
removed. Additionally, there is a new user pref for persisting
creation times across sessions.

Test: manual
Bug: 1133391
Change-Id: I78a5e310a4bcfad57727de04adffc91b3af945c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2712983
Commit-Queue: Jeremy Chinsen <chinsenj@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#859839}

ash/public/cpp/ash_pref_names.cc

@@ -169,6 +169,10 @@ const char kContextualTooltips[] = "settings.contextual_tooltip.shown_info";
 // name will appear in this list as an empty string. The desk names are stored
 // as UTF8 strings.
 const char kDesksNamesList[] = "ash.desks.desks_names_list";
+// This list stores the metrics of virtual desks. Like |kDesksNamesList|, this
+// list stores entries in the same order of the desks in the overview desks bar.
+// Values are stored as dictionaries.
+const char kDesksMetricsList[] = "ash.desks.desks_metrics_list";
 // An integer index of a user's active desk.
 const char kDesksActiveDesk[] = "ash.desks.active_desk";
 

ash/public/cpp/ash_pref_names.h

@@ -66,6 +66,7 @@ ASH_PUBLIC_EXPORT extern const char kAltTabPerDesk[];
 ASH_PUBLIC_EXPORT extern const char kContextualTooltips[];
 
 ASH_PUBLIC_EXPORT extern const char kDesksNamesList[];
+ASH_PUBLIC_EXPORT extern const char kDesksMetricsList[];
 ASH_PUBLIC_EXPORT extern const char kDesksActiveDesk[];
 
 ASH_PUBLIC_EXPORT extern const char kDockedMagnifierEnabled[];

ash/wm/desks/desk.cc

@@ -25,6 +25,7 @@
 #include "ash/wm/workspace_controller.h"
 #include "base/containers/adapters.h"
 #include "base/containers/contains.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/stl_util.h"
 #include "chromeos/ui/base/window_properties.h"
 #include "ui/aura/client/aura_constants.h"
@@ -36,6 +37,9 @@ namespace ash {
 
 namespace {
 
+// Prefix for the desks lifetime histogram.
+constexpr char kDeskLifetimeHistogramNamePrefix[] = "Ash.Desks.DeskLifetime_";
+
 void UpdateBackdropController(aura::Window* desk_container) {
   auto* workspace_controller = GetWorkspaceController(desk_container);
   // Work might have already been cleared when the display is removed. See
@@ -180,7 +184,8 @@ class DeskContainerObserver : public aura::WindowObserver {
 // Desk:
 
 Desk::Desk(int associated_container_id)
-    : container_id_(associated_container_id) {
+    : container_id_(associated_container_id),
+      creation_time_(base::Time::Now()) {
   // For the very first default desk added during initialization, there won't be
   // any root windows yet. That's OK, OnRootWindowAdded() will be called
   // explicitly by the RootWindowController when they're initialized.
@@ -489,6 +494,15 @@ void Desk::SetDeskBeingRemoved() {
   is_desk_being_removed_ = true;
 }
 
+void Desk::RecordLifetimeHistogram() {
+  // Desk index is 1-indexed in histograms.
+  const int desk_index =
+      Shell::Get()->desks_controller()->GetDeskIndex(this) + 1;
+  base::UmaHistogramCounts1000(
+      base::StringPrintf("%s%i", kDeskLifetimeHistogramNamePrefix, desk_index),
+      (base::Time::Now() - creation_time_).InHours());
+}
+
 void Desk::MoveWindowToDeskInternal(aura::Window* window,
                                     Desk* target_desk,
                                     aura::Window* target_root) {

ash/wm/desks/desk.h

@@ -14,6 +14,7 @@
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
+#include "base/time/time.h"
 #include "ui/aura/window_observer.h"
 
 namespace ash {
@@ -54,6 +55,8 @@ class ASH_EXPORT Desk {
 
   const std::vector<aura::Window*>& windows() const { return windows_; }
 
+  const base::Time& creation_time() const { return creation_time_; }
+
   const base::string16& name() const { return name_; }
 
   bool is_active() const { return is_active_; }
@@ -66,6 +69,12 @@ class ASH_EXPORT Desk {
 
   bool is_name_set_by_user() const { return is_name_set_by_user_; }
 
+  // Sets the desk's |creation_time_| to |creation_time|. This will overwrite
+  // |creation_time_| so this should only be called when restoring desks.
+  void set_creation_time(base::Time creation_time) {
+    creation_time_ = creation_time;
+  }
+
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
@@ -130,6 +139,10 @@ class ASH_EXPORT Desk {
   // when desk is already removed from |desks_| in DesksController.
   void SetDeskBeingRemoved();
 
+  // Records the lifetime of the desk based on its desk index. Should be called
+  // when this desk is removed by the user.
+  void RecordLifetimeHistogram();
+
  private:
   void MoveWindowToDeskInternal(aura::Window* window,
                                 Desk* target_desk,
@@ -181,6 +194,9 @@ class ASH_EXPORT Desk {
   // True if the desk is being removed.
   bool is_desk_being_removed_ = false;
 
+  // The time this desk was created at. Used to record desk lifetimes.
+  base::Time creation_time_;
+
   DISALLOW_COPY_AND_ASSIGN(Desk);
 };
 

ash/wm/desks/desks_controller.cc

@@ -372,6 +372,7 @@ void DesksController::NewDesk(DesksCreationRemovalSource source) {
 
   if (!is_first_ever_desk) {
     desks_restore_util::UpdatePrimaryUserDeskNamesPrefs();
+    desks_restore_util::UpdatePrimaryUserDeskMetricsPrefs();
     UMA_HISTOGRAM_ENUMERATION(kNewDeskHistogramName, source);
     ReportDesksCountHistogram();
   }
@@ -422,8 +423,10 @@ void DesksController::ReorderDesk(int old_index, int new_index) {
   // Meanwhile, only the primary user needs to update the active desk, which is
   // independent across profiles but only recoverable for the primary user.
 
-  // 1. Update desk name list in the user prefs to maintain the right order.
+  // 1. Update desk name and metrics lists in the user prefs to maintain the
+  // right order.
   desks_restore_util::UpdatePrimaryUserDeskNamesPrefs();
+  desks_restore_util::UpdatePrimaryUserDeskMetricsPrefs();
 
   // 2. For multi-profile switching, update all affected active desk index in
   // |user_to_active_desk_index_|.
@@ -673,6 +676,14 @@ void DesksController::RestoreNameOfDeskAtIndex(base::string16 name,
   desks_[index]->SetName(std::move(name), /*set_by_user=*/true);
 }
 
+void DesksController::RestoreMetricsOfDeskAtIndex(base::Time creation_time,
+                                                  size_t index) {
+  DCHECK_LT(index, desks_.size());
+
+  const auto& target_desk = desks_[index];
+  target_desk->set_creation_time(std::move(creation_time));
+}
+
 void DesksController::OnRootWindowAdded(aura::Window* root_window) {
   for (auto& desk : desks_)
     desk->OnRootWindowAdded(root_window);
@@ -886,6 +897,9 @@ void DesksController::RemoveDeskInternal(const Desk* desk,
   // Used by accessibility to indicate the desk that has been removed.
   const int removed_desk_number = std::distance(desks_.begin(), iter) + 1;
 
+  // Record |desk|'s lifetime before it's removed from |desks_|.
+  const_cast<Desk*>(desk)->RecordLifetimeHistogram();
+
   // Keep the removed desk alive until the end of this function.
   std::unique_ptr<Desk> removed_desk = std::move(*iter);
   removed_desk->SetDeskBeingRemoved();
@@ -1017,6 +1031,7 @@ void DesksController::RemoveDeskInternal(const Desk* desk,
           active_desk_->name()));
 
   desks_restore_util::UpdatePrimaryUserDeskNamesPrefs();
+  desks_restore_util::UpdatePrimaryUserDeskMetricsPrefs();
 
   DCHECK_LE(available_container_ids_.size(), desks_util::GetMaxNumberOfDesks());
 }

ash/wm/desks/desks_controller.h

@@ -190,11 +190,14 @@ class ASH_EXPORT DesksController : public DesksHelper,
   // it was never modified by users.
   void RevertDeskNameToDefault(Desk* desk);
 
-  // Restores the desk at |index| to the given |name|. This is only for user-
-  // modified desk names, and hence |name| should never be empty since users are
-  // not allowed to set empty names.
+  // Restores the desk at |index| to the given |name|. This is only for
+  // user-modified desk names, and hence |name| should never be empty since
+  // users are not allowed to set empty names.
   void RestoreNameOfDeskAtIndex(base::string16 name, size_t index);
 
+  // Restores the metrics of the desk at |index|.
+  void RestoreMetricsOfDeskAtIndex(base::Time creation_time, size_t index);
+
   // Called explicitly by the RootWindowController when a root window has been
   // added or about to be removed in order to update all the available desks.
   void OnRootWindowAdded(aura::Window* root_window);

ash/wm/desks/desks_restore_util.cc

@@ -25,6 +25,11 @@ namespace desks_restore_util {
 
 namespace {
 
+// Keys for the dictionaries stored in |kDesksMetricsList|. The entry is an int
+// which represents the number of minutes for
+// base::Time::FromDeltaSinceWindowsEpoch().
+constexpr char kCreationTimeKey[] = "creation_time";
+
 // While restore is in progress, changes are being made to the desks and their
 // names. Those changes should not trigger an update to the prefs.
 bool g_pause_desks_prefs_updates = false;
@@ -46,6 +51,7 @@ bool IsValidDeskIndex(int desk_index) {
 void RegisterProfilePrefs(PrefRegistrySimple* registry) {
   constexpr int kDefaultActiveDeskIndex = 0;
   registry->RegisterListPref(prefs::kDesksNamesList);
+  registry->RegisterListPref(prefs::kDesksMetricsList);
   if (features::IsBentoEnabled()) {
     registry->RegisterIntegerPref(prefs::kDesksActiveDesk,
                                   kDefaultActiveDeskIndex);
@@ -61,11 +67,13 @@ void RestorePrimaryUserDesks() {
     return;
   }
 
-  const base::ListValue* desks_names_list =
+  const base::ListValue* desks_names =
       primary_user_prefs->GetList(prefs::kDesksNamesList);
+  const base::ListValue* desks_metrics =
+      primary_user_prefs->GetList(prefs::kDesksMetricsList);
 
   // First create the same number of desks.
-  const size_t restore_size = desks_names_list->GetSize();
+  const size_t restore_size = desks_names->GetSize();
 
   // If we don't have any restore data, or the list is corrupt for some reason,
   // abort.
@@ -76,9 +84,12 @@ void RestorePrimaryUserDesks() {
   while (desks_controller->desks().size() < restore_size)
     desks_controller->NewDesk(DesksCreationRemovalSource::kDesksRestore);
 
-  size_t index = 0;
-  for (const auto& value : desks_names_list->GetList()) {
-    const std::string& desk_name = value.GetString();
+  const auto& desks_names_list = desks_names->GetList();
+  const auto& desks_metrics_list = desks_metrics->GetList();
+  const size_t desks_metrics_list_size = desks_metrics->GetSize();
+  const auto now = base::Time::Now();
+  for (size_t index = 0; index < restore_size; ++index) {
+    const std::string& desk_name = desks_names_list[index].GetString();
     // Empty desks names are just place holders for desks whose names haven't
     // been modified by the user. Those don't need to be restored; they already
     // have the correct default names based on their positions in the desks
@@ -87,7 +98,20 @@ void RestorePrimaryUserDesks() {
       desks_controller->RestoreNameOfDeskAtIndex(base::UTF8ToUTF16(desk_name),
                                                  index);
     }
-    ++index;
+
+    if (index >= desks_metrics_list_size)
+      continue;
+
+    // Only restore metrics if there is existing data.
+    const auto& desks_metrics_dict = desks_metrics_list[index];
+    const auto& creation_time_entry =
+        desks_metrics_dict.FindIntPath(kCreationTimeKey);
+    if (creation_time_entry.has_value()) {
+      const auto creation_time = base::Time::FromDeltaSinceWindowsEpoch(
+          base::TimeDelta::FromMinutes(*creation_time_entry));
+      if (!creation_time.is_null() && creation_time < now)
+        desks_controller->RestoreMetricsOfDeskAtIndex(creation_time, index);
+    }
   }
 
   // Restore an active desk for the primary user.
@@ -114,20 +138,47 @@ void UpdatePrimaryUserDeskNamesPrefs() {
     return;
   }
 
-  ListPrefUpdate update(primary_user_prefs, prefs::kDesksNamesList);
-  base::ListValue* pref_data = update.Get();
-  pref_data->Clear();
+  ListPrefUpdate name_update(primary_user_prefs, prefs::kDesksNamesList);
+  base::ListValue* name_pref_data = name_update.Get();
+  name_pref_data->Clear();
+
   const auto& desks = DesksController::Get()->desks();
   for (const auto& desk : desks) {
     // Desks whose names were not changed by the user, are stored as empty
     // strings. They're just place holders to restore the correct desks count.
     // RestorePrimaryUserDesks() restores only non-empty desks names.
-    pref_data->Append(desk->is_name_set_by_user()
-                          ? base::UTF16ToUTF8(desk->name())
-                          : std::string());
+    name_pref_data->Append(desk->is_name_set_by_user()
+                               ? base::UTF16ToUTF8(desk->name())
+                               : std::string());
+  }
+
+  DCHECK_EQ(name_pref_data->GetSize(), desks.size());
+}
+
+void UpdatePrimaryUserDeskMetricsPrefs() {
+  if (g_pause_desks_prefs_updates)
+    return;
+
+  PrefService* primary_user_prefs = GetPrimaryUserPrefService();
+  if (!primary_user_prefs) {
+    // Can be null in tests.
+    return;
+  }
+
+  ListPrefUpdate metrics_update(primary_user_prefs, prefs::kDesksMetricsList);
+  base::ListValue* metrics_pref_data = metrics_update.Get();
+  metrics_pref_data->Clear();
+
+  const auto& desks = DesksController::Get()->desks();
+  for (const auto& desk : desks) {
+    base::DictionaryValue metrics_dict;
+    metrics_dict.SetInteger(
+        kCreationTimeKey,
+        desk->creation_time().ToDeltaSinceWindowsEpoch().InMinutes());
+    metrics_pref_data->Append(std::move(metrics_dict));
   }
 
-  DCHECK_EQ(pref_data->GetSize(), desks.size());
+  DCHECK_EQ(metrics_pref_data->GetSize(), desks.size());
 }
 
 void UpdatePrimaryUserActiveDeskPrefs(int active_desk_index) {

ash/wm/desks/desks_restore_util.h

@@ -24,6 +24,10 @@ void RestorePrimaryUserDesks();
 // desks count or a desk name changes.
 ASH_EXPORT void UpdatePrimaryUserDeskNamesPrefs();
 
+// Called to update the desk metrics restore prefs for the primary user whenever
+// desks count changes or desks reordered.
+ASH_EXPORT void UpdatePrimaryUserDeskMetricsPrefs();
+
 // Called to update the active desk restore prefs for the primary user whenever
 // the primary user switches an active desk.
 void UpdatePrimaryUserActiveDeskPrefs(int active_desk_index);

tools/metrics/histograms/histograms_xml/ash/histograms.xml

@@ -634,6 +634,26 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Ash.Desks.DeskLifetime_{DeskIndex}" units="hr"
+    expires_after="2022-02-19">
+  <owner>chinsenj@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The lifetime of the desk at index {DeskIndex} (1-indexed). Emitted when a
+    desk is removed. This metric is persisted across sessions.
+  </summary>
+  <token key="DeskIndex">
+    <variant name="1" summary="1"/>
+    <variant name="2" summary="2"/>
+    <variant name="3" summary="3"/>
+    <variant name="4" summary="4"/>
+    <variant name="5" summary="5"/>
+    <variant name="6" summary="6"/>
+    <variant name="7" summary="7"/>
+    <variant name="8" summary="8"/>
+  </token>
+</histogram>
+
 <histogram name="Ash.Desks.DesksCount2" units="units"
     expires_after="2021-11-29">
   <owner>afakhry@chromium.org</owner>