ash: Adding flag to enable 16 virtual desks.

When the flag (enable-16-desks) is enabled, up to 16 virtual desks can
be created, up from the default 8.

Most of the changes are related to the constant kMaxNumberOfDesks
changing to the function GetMaxNumberOfDesks.

The unit tests in desks_unittests have been updated to work with either
8 or 16 desks. Additionally, they have been parameterized so that going
forward, we will test with both 8 and 16 desks.

Bug: b/250957096


Change-Id: I7d0506f8ccfac4d3b891e340c6694cf99f7d4b0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3928065
Reviewed-by: Richard Chui <richui@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Commit-Queue: Daniel Andersson <dandersson@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1058389}

ash/ash_strings.grd

@@ -2012,6 +2012,30 @@ This file contains the strings for ash.
       <message name="IDS_ASH_DESKS_DESK_8_MINI_VIEW_TITLE" desc="The label of the eighth virtual desk thumbnail.">
         Desk 8
       </message>
+      <message name="IDS_ASH_DESKS_DESK_9_MINI_VIEW_TITLE" desc="The label of the ninth virtual desk thumbnail.">
+        Desk 9
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_10_MINI_VIEW_TITLE" desc="The label of the tenth virtual desk thumbnail.">
+        Desk 10
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_11_MINI_VIEW_TITLE" desc="The label of the eleventh virtual desk thumbnail.">
+        Desk 11
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_12_MINI_VIEW_TITLE" desc="The label of the twelfth virtual desk thumbnail.">
+        Desk 12
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_13_MINI_VIEW_TITLE" desc="The label of the thirteenth virtual desk thumbnail.">
+        Desk 13
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_14_MINI_VIEW_TITLE" desc="The label of the fourteenth virtual desk thumbnail.">
+        Desk 14
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_15_MINI_VIEW_TITLE" desc="The label of the fifteenth virtual desk thumbnail.">
+        Desk 15
+      </message>
+      <message name="IDS_ASH_DESKS_DESK_16_MINI_VIEW_TITLE" desc="The label of the sixteenth virtual desk thumbnail.">
+        Desk 16
+      </message>
       <message name="IDS_ASH_DESKS_MAX_NUM_REACHED" desc="Message shown to users when they attempt to add a new virtual desk when the maximum number of desks has been reached.">
         Maximum number of desks reached.
       </message>

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_10_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+5734ddc2b3616da0363ef3915f8140047c3fd679

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_11_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+4b01ef86b4f18673e366f0daa288c81b24632d72

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_12_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+0e20c93104f0c3f888799858ab1ac602b6fc2895

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_13_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+37c590fe6a4e29648d256d3d46d659fc1c39f2be

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_14_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+5c910096df22f0d70a42f2932679657316c0f1ff

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_15_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+c8e2cc7de44021c8fcba1df1f005d1e46a56996e

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_16_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+9746407f33db29d2cfaf7a3f2935789ccb0a55a3

ash/ash_strings_grd/IDS_ASH_DESKS_DESK_9_MINI_VIEW_TITLE.png.sha1

@@ -0,0 +1 @@
+d40bf6abd2477ead797905d83556bfc37914615b

ash/constants/ash_features.cc

@@ -686,6 +686,11 @@ BASE_FEATURE(kEcheSWADisableStunServer,
              "EcheSWADisableStunServer",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
+// If enabled, allows the creation of up to 16 desks (default is 8).
+BASE_FEATURE(kEnable16Desks,
+             "Enable16Desks",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
 // Enables background blur for the app list, shelf, unified system tray,
 // autoclick menu, etc. Also enables the AppsGridView mask layer, slower devices
 // may have choppier app list animations while in this mode. crbug.com/765292.
@@ -2176,6 +2181,10 @@ bool DoWindowsFollowCursor() {
   return base::FeatureList::IsEnabled(kWindowsFollowCursor);
 }
 
+bool Is16DesksEnabled() {
+  return base::FeatureList::IsEnabled(kEnable16Desks);
+}
+
 bool IsAdaptiveChargingEnabled() {
   return base::FeatureList::IsEnabled(kAdaptiveCharging);
 }

ash/constants/ash_features.h

@@ -241,6 +241,7 @@ BASE_DECLARE_FEATURE(kEnableOobeNetworkScreenSkip);
 COMPONENT_EXPORT(ASH_CONSTANTS) BASE_DECLARE_FEATURE(kEnableOobeThemeSelection);
 COMPONENT_EXPORT(ASH_CONSTANTS)
 BASE_DECLARE_FEATURE(kEnableSamlNotificationOnPasswordChangeSuccess);
+COMPONENT_EXPORT(ASH_CONSTANTS) BASE_DECLARE_FEATURE(kEnable16Desks);
 COMPONENT_EXPORT(ASH_CONSTANTS) BASE_DECLARE_FEATURE(kEnableSavedDesks);
 COMPONENT_EXPORT(ASH_CONSTANTS) BASE_DECLARE_FEATURE(kEnableAllSystemWebApps);
 COMPONENT_EXPORT(ASH_CONSTANTS)
@@ -601,6 +602,7 @@ COMPONENT_EXPORT(ASH_CONSTANTS) bool IsAutocompleteExtendedSuggestionsEnabled();
 COMPONENT_EXPORT(ASH_CONSTANTS) bool IsAvatarsCloudMigrationEnabled();
 COMPONENT_EXPORT(ASH_CONSTANTS) bool AreImprovedScreenCaptureSettingsEnabled();
 COMPONENT_EXPORT(ASH_CONSTANTS) bool DoWindowsFollowCursor();
+COMPONENT_EXPORT(ASH_CONSTANTS) bool Is16DesksEnabled();
 COMPONENT_EXPORT(ASH_CONSTANTS) bool IsAdaptiveChargingEnabled();
 COMPONENT_EXPORT(ASH_CONSTANTS) bool IsAdaptiveChargingForTestingEnabled();
 COMPONENT_EXPORT(ASH_CONSTANTS) bool IsAdjustSplitViewForVKEnabled();

ash/public/cpp/shell_window_ids.cc

@@ -44,23 +44,34 @@ constexpr std::array<int, 5> kPostDesksActivatableContainersIds = {
     kShellWindowId_ShelfBubbleContainer,
 };
 
+// List of desk container IDs. Can't use desks_util since we're in ash/public
+// here.
+constexpr std::array<int, 16> kDeskContainerIds = {
+    kShellWindowId_DefaultContainerDeprecated,
+    kShellWindowId_DeskContainerB,
+    kShellWindowId_DeskContainerC,
+    kShellWindowId_DeskContainerD,
+    kShellWindowId_DeskContainerE,
+    kShellWindowId_DeskContainerF,
+    kShellWindowId_DeskContainerG,
+    kShellWindowId_DeskContainerH,
+    kShellWindowId_DeskContainerI,
+    kShellWindowId_DeskContainerJ,
+    kShellWindowId_DeskContainerK,
+    kShellWindowId_DeskContainerL,
+    kShellWindowId_DeskContainerM,
+    kShellWindowId_DeskContainerN,
+    kShellWindowId_DeskContainerO,
+    kShellWindowId_DeskContainerP,
+};
+
 }  // namespace
 
 std::vector<int> GetActivatableShellWindowIds() {
   std::vector<int> ids(kPreDesksActivatableContainersIds.begin(),
                        kPreDesksActivatableContainersIds.end());
 
-  // Add the desks containers IDs. Can't use desks_util since we're in
-  // ash/public here.
-  ids.emplace_back(kShellWindowId_DefaultContainerDeprecated);
-  ids.emplace_back(kShellWindowId_DeskContainerB);
-  ids.emplace_back(kShellWindowId_DeskContainerC);
-  ids.emplace_back(kShellWindowId_DeskContainerD);
-  ids.emplace_back(kShellWindowId_DeskContainerE);
-  ids.emplace_back(kShellWindowId_DeskContainerF);
-  ids.emplace_back(kShellWindowId_DeskContainerG);
-  ids.emplace_back(kShellWindowId_DeskContainerH);
-
+  ids.insert(ids.end(), kDeskContainerIds.begin(), kDeskContainerIds.end());
   ids.insert(ids.end(), kPostDesksActivatableContainersIds.begin(),
              kPostDesksActivatableContainersIds.end());
   return ids;

ash/public/cpp/shell_window_ids.h

@@ -78,6 +78,14 @@ enum ShellWindowId {
   kShellWindowId_DeskContainerF,
   kShellWindowId_DeskContainerG,
   kShellWindowId_DeskContainerH,
+  kShellWindowId_DeskContainerI,
+  kShellWindowId_DeskContainerJ,
+  kShellWindowId_DeskContainerK,
+  kShellWindowId_DeskContainerL,
+  kShellWindowId_DeskContainerM,
+  kShellWindowId_DeskContainerN,
+  kShellWindowId_DeskContainerO,
+  kShellWindowId_DeskContainerP,
 
   // The container for top-level windows with the 'always-on-top' flag set.
   kShellWindowId_AlwaysOnTopContainer,

ash/wm/desks/autotest_desks_api_unittests.cc

@@ -69,7 +69,7 @@ TEST_F(AutotestDesksApiTest, ActivateDeskAtIndex) {
   auto* controller = DesksController::Get();
   while (controller->CanCreateDesks())
     EXPECT_TRUE(test_api.CreateNewDesk());
-  EXPECT_EQ(desks_util::kMaxNumberOfDesks, controller->desks().size());
+  EXPECT_EQ(desks_util::GetMaxNumberOfDesks(), controller->desks().size());
   constexpr int kIndices[] = {1, 2, 3, 0};
   for (const int index : kIndices) {
     base::RunLoop run_loop;
@@ -83,7 +83,7 @@ TEST_F(AutotestDesksApiTest, RemoveActiveDesk) {
   AutotestDesksApi test_api;
   EXPECT_FALSE(test_api.RemoveActiveDesk(base::DoNothing()));
 
-  const size_t max_number_of_desks = desks_util::kMaxNumberOfDesks;
+  const size_t max_number_of_desks = desks_util::GetMaxNumberOfDesks();
   auto* controller = DesksController::Get();
   while (controller->CanCreateDesks())
     EXPECT_TRUE(test_api.CreateNewDesk());
@@ -114,7 +114,7 @@ TEST_F(EnhancedDeskAnimationsAutotestDesksApiTest,
        DISABLED_ActivateAdjacentDesksToTargetIndex) {
   // Create all desks possible.
   AutotestDesksApi test_api;
-  const int max_number_of_desks = desks_util::kMaxNumberOfDesks;
+  const int max_number_of_desks = desks_util::GetMaxNumberOfDesks();
   auto* controller = DesksController::Get();
   while (controller->CanCreateDesks())
     EXPECT_TRUE(test_api.CreateNewDesk());
@@ -127,7 +127,7 @@ TEST_F(EnhancedDeskAnimationsAutotestDesksApiTest,
   // Activating already active desk does nothing.
   EXPECT_FALSE(
       test_api.ActivateAdjacentDesksToTargetIndex(0, base::DoNothing()));
-  EXPECT_EQ(desks_util::kMaxNumberOfDesks, controller->desks().size());
+  EXPECT_EQ(desks_util::GetMaxNumberOfDesks(), controller->desks().size());
 
   // Replacing needs to be done while a current animation is underway, otherwise
   // it will have no effect.

ash/wm/desks/desks_controller.cc

@@ -104,23 +104,9 @@ constexpr char kNumberOfWindowsClosedBySaveAndRecall[] =
     "Ash.Desks.NumberOfWindowsClosed.SaveRecall";
 constexpr char kNumberOfWindowsClosedByApi[] =
     "Ash.Desks.NumberOfWindowsClosed.Api";
-
-constexpr char kNumberOfWindowsOnDesk_1_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_1";
-constexpr char kNumberOfWindowsOnDesk_2_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_2";
-constexpr char kNumberOfWindowsOnDesk_3_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_3";
-constexpr char kNumberOfWindowsOnDesk_4_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_4";
-constexpr char kNumberOfWindowsOnDesk_5_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_5";
-constexpr char kNumberOfWindowsOnDesk_6_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_6";
-constexpr char kNumberOfWindowsOnDesk_7_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_7";
-constexpr char kNumberOfWindowsOnDesk_8_HistogramName[] =
-    "Ash.Desks.NumberOfWindowsOnDesk_8";
+// Used for histograms from "Ash.Desks.NumberOfWindowsOnDesk_1" up to 16.
+constexpr char kNumberOfWindowsOnDeskHistogramPrefix[] =
+    "Ash.Desks.NumberOfWindowsOnDesk_";
 
 constexpr char kNumberOfDeskTraversalsHistogramName[] =
     "Ash.Desks.NumberOfDeskTraversals";
@@ -132,10 +118,23 @@ constexpr int kDeskTraversalsMaxValue = 20;
 constexpr base::TimeDelta kDeskTraversalsTimeout = base::Seconds(5);
 
 constexpr int kDeskDefaultNameIds[] = {
-    IDS_ASH_DESKS_DESK_1_MINI_VIEW_TITLE, IDS_ASH_DESKS_DESK_2_MINI_VIEW_TITLE,
-    IDS_ASH_DESKS_DESK_3_MINI_VIEW_TITLE, IDS_ASH_DESKS_DESK_4_MINI_VIEW_TITLE,
-    IDS_ASH_DESKS_DESK_5_MINI_VIEW_TITLE, IDS_ASH_DESKS_DESK_6_MINI_VIEW_TITLE,
-    IDS_ASH_DESKS_DESK_7_MINI_VIEW_TITLE, IDS_ASH_DESKS_DESK_8_MINI_VIEW_TITLE};
+    IDS_ASH_DESKS_DESK_1_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_2_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_3_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_4_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_5_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_6_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_7_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_8_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_9_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_10_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_11_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_12_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_13_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_14_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_15_MINI_VIEW_TITLE,
+    IDS_ASH_DESKS_DESK_16_MINI_VIEW_TITLE,
+};
 
 // Appends the given |windows| to the end of the currently active overview mode
 // session such that the most-recently used window is added first. If
@@ -419,7 +418,7 @@ DesksController* DesksController::Get() {
 
 // static
 std::u16string DesksController::GetDeskDefaultName(size_t desk_index) {
-  DCHECK_LT(desk_index, desks_util::kMaxNumberOfDesks);
+  DCHECK_LT(desk_index, desks_util::GetMaxNumberOfDesks());
   return l10n_util::GetStringUTF16(kDeskDefaultNameIds[desk_index]);
 }
 
@@ -493,7 +492,7 @@ bool DesksController::AreDesksBeingModified() const {
 }
 
 bool DesksController::CanCreateDesks() const {
-  return desks_.size() < desks_util::kMaxNumberOfDesks;
+  return desks_.size() < desks_util::GetMaxNumberOfDesks();
 }
 
 Desk* DesksController::GetNextDesk(bool use_target_active_desk) const {
@@ -1699,7 +1698,7 @@ void DesksController::RemoveDeskInternal(const Desk* desk,
   desks_restore_util::UpdatePrimaryUserDeskNamesPrefs();
   desks_restore_util::UpdatePrimaryUserDeskMetricsPrefs();
 
-  DCHECK_LE(available_container_ids_.size(), desks_util::kMaxNumberOfDesks);
+  DCHECK_LE(available_container_ids_.size(), desks_util::GetMaxNumberOfDesks());
 
   if (close_type == DeskCloseType::kCloseAllWindowsAndWait) {
     ShowDeskRemovalUndoToast(
@@ -1961,60 +1960,19 @@ void DesksController::GetAllDesks(std::vector<const Desk*>& out_desks) const {
 }
 
 void DesksController::ReportNumberOfWindowsPerDeskHistogram() const {
+  DCHECK_LE(desks_.size(), desks_util::kDesksUpperLimit);
   for (size_t i = 0; i < desks_.size(); ++i) {
     const size_t windows_count = desks_[i]->windows().size();
-    switch (i) {
-      case 0:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_1_HistogramName,
-                                 windows_count);
-        break;
-
-      case 1:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_2_HistogramName,
-                                 windows_count);
-        break;
-
-      case 2:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_3_HistogramName,
-                                 windows_count);
-        break;
-
-      case 3:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_4_HistogramName,
-                                 windows_count);
-        break;
-
-      case 4:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_5_HistogramName,
-                                 windows_count);
-        break;
-
-      case 5:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_6_HistogramName,
-                                 windows_count);
-        break;
-
-      case 6:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_7_HistogramName,
-                                 windows_count);
-        break;
-
-      case 7:
-        UMA_HISTOGRAM_COUNTS_100(kNumberOfWindowsOnDesk_8_HistogramName,
-                                 windows_count);
-        break;
-
-      default:
-        NOTREACHED();
-        break;
-    }
+    base::UmaHistogramCounts100(
+        kNumberOfWindowsOnDeskHistogramPrefix + base::NumberToString(i + 1),
+        windows_count);
   }
 }
 
 void DesksController::ReportDesksCountHistogram() const {
-  DCHECK_LE(desks_.size(), desks_util::kMaxNumberOfDesks);
+  DCHECK_LE(desks_.size(), desks_util::kDesksUpperLimit);
   UMA_HISTOGRAM_EXACT_LINEAR(kDesksCountHistogramName, desks_.size(),
-                             desks_util::kMaxNumberOfDesks);
+                             desks_util::kDesksUpperLimit + 1);
 }
 
 void DesksController::RecordAndResetNumberOfWeeklyActiveDesks() {

ash/wm/desks/desks_restore_util.cc

@@ -80,9 +80,7 @@ PrefService* GetPrimaryUserPrefService() {
 // DesksController.
 bool IsValidDeskIndex(int desk_index) {
   return desk_index >= 0 &&
-         desk_index <
-             static_cast<int>(DesksController::Get()->desks().size()) &&
-         desk_index < int{desks_util::kMaxNumberOfDesks};
+         desk_index < static_cast<int>(DesksController::Get()->desks().size());
 }
 
 base::Time GetTime(int year, int month, int day_of_month, int day_of_week) {
@@ -151,13 +149,16 @@ void RestorePrimaryUserDesks() {
       primary_user_prefs->GetList(prefs::kDesksMetricsList);
 
   // First create the same number of desks.
-  const size_t restore_size = desks_names_list.size();
+  size_t restore_size = desks_names_list.size();
 
-  // If we don't have any restore data, or the list is corrupt for some reason,
-  // abort.
-  if (!restore_size || restore_size > desks_util::kMaxNumberOfDesks)
+  // If we don't have any restore data, abort.
+  if (restore_size == 0)
     return;
 
+  // If we have more restore data than the *current* max, clamp it. This can
+  // happen if the restore data was created when more desks were permitted.
+  restore_size = std::min(restore_size, desks_util::GetMaxNumberOfDesks());
+
   auto* desks_controller = DesksController::Get();
   while (desks_controller->desks().size() < restore_size)
     desks_controller->NewDesk(DesksCreationRemovalSource::kDesksRestore);

ash/wm/desks/desks_util.cc

@@ -6,6 +6,7 @@
 
 #include <array>
 
+#include "ash/constants/ash_features.h"
 #include "ash/public/cpp/tablet_mode.h"
 #include "ash/shell.h"
 #include "ash/wm/desks/desk.h"
@@ -25,7 +26,7 @@ namespace desks_util {
 
 namespace {
 
-constexpr std::array<int, kMaxNumberOfDesks> kDesksContainersIds = {
+constexpr std::array<int, kDesksUpperLimit> kDesksContainersIds = {
     kShellWindowId_DefaultContainerDeprecated,
     kShellWindowId_DeskContainerB,
     kShellWindowId_DeskContainerC,
@@ -34,13 +35,28 @@ constexpr std::array<int, kMaxNumberOfDesks> kDesksContainersIds = {
     kShellWindowId_DeskContainerF,
     kShellWindowId_DeskContainerG,
     kShellWindowId_DeskContainerH,
+    kShellWindowId_DeskContainerI,
+    kShellWindowId_DeskContainerJ,
+    kShellWindowId_DeskContainerK,
+    kShellWindowId_DeskContainerL,
+    kShellWindowId_DeskContainerM,
+    kShellWindowId_DeskContainerN,
+    kShellWindowId_DeskContainerO,
+    kShellWindowId_DeskContainerP,
 };
 
+// Default max number of desks (that is, enable-16-desks is off).
+constexpr size_t kDesksDefaultLimit = 8;
+
 }  // namespace
 
+size_t GetMaxNumberOfDesks() {
+  return features::Is16DesksEnabled() ? kDesksUpperLimit : kDesksDefaultLimit;
+}
+
 std::vector<int> GetDesksContainersIds() {
   return std::vector<int>(kDesksContainersIds.begin(),
-                          kDesksContainersIds.end());
+                          kDesksContainersIds.begin() + GetMaxNumberOfDesks());
 }
 
 std::vector<aura::Window*> GetDesksContainers(aura::Window* root) {
@@ -85,6 +101,30 @@ const char* GetDeskContainerName(int container_id) {
     case kShellWindowId_DeskContainerH:
       return "Desk_Container_H";
 
+    case kShellWindowId_DeskContainerI:
+      return "Desk_Container_I";
+
+    case kShellWindowId_DeskContainerJ:
+      return "Desk_Container_J";
+
+    case kShellWindowId_DeskContainerK:
+      return "Desk_Container_K";
+
+    case kShellWindowId_DeskContainerL:
+      return "Desk_Container_L";
+
+    case kShellWindowId_DeskContainerM:
+      return "Desk_Container_M";
+
+    case kShellWindowId_DeskContainerN:
+      return "Desk_Container_N";
+
+    case kShellWindowId_DeskContainerO:
+      return "Desk_Container_O";
+
+    case kShellWindowId_DeskContainerP:
+      return "Desk_Container_P";
+
     default:
       NOTREACHED();
       return "";
@@ -104,7 +144,15 @@ bool IsDeskContainerId(int id) {
          id == kShellWindowId_DeskContainerE ||
          id == kShellWindowId_DeskContainerF ||
          id == kShellWindowId_DeskContainerG ||
-         id == kShellWindowId_DeskContainerH;
+         id == kShellWindowId_DeskContainerH ||
+         id == kShellWindowId_DeskContainerI ||
+         id == kShellWindowId_DeskContainerJ ||
+         id == kShellWindowId_DeskContainerK ||
+         id == kShellWindowId_DeskContainerL ||
+         id == kShellWindowId_DeskContainerM ||
+         id == kShellWindowId_DeskContainerN ||
+         id == kShellWindowId_DeskContainerO ||
+         id == kShellWindowId_DeskContainerP;
 }
 
 int GetActiveDeskContainerId() {

ash/wm/desks/desks_util.h

@@ -25,7 +25,12 @@ namespace ash {
 
 namespace desks_util {
 
-constexpr size_t kMaxNumberOfDesks = 8;
+// Note: the max number of desks depends on a runtime flag and the function
+// `GetMaxNumberOfDesks` below will return that value. The value returned from
+// that function will not be more than this constant.
+constexpr size_t kDesksUpperLimit = 16;
+
+ASH_EXPORT size_t GetMaxNumberOfDesks();
 
 ASH_EXPORT std::vector<int> GetDesksContainersIds();
 

ash/wm/desks/root_window_desk_switch_animator.cc

@@ -120,7 +120,7 @@ RootWindowDeskSwitchAnimator::RootWindowDeskSwitchAnimator(
   DCHECK_NE(starting_desk_index_, ending_desk_index_);
   DCHECK(delegate_);
 
-  screenshot_layers_.resize(desks_util::kMaxNumberOfDesks);
+  screenshot_layers_.resize(desks_util::GetMaxNumberOfDesks());
 }
 
 RootWindowDeskSwitchAnimator::~RootWindowDeskSwitchAnimator() {

ash/wm/desks/templates/saved_desk_presenter.cc

@@ -409,7 +409,7 @@ void SavedDeskPresenter::LaunchSavedDesk(
         /*text=*/
         l10n_util::GetStringFUTF16(
             IDS_ASH_DESKS_TEMPLATES_REACH_MAXIMUM_DESK_TOAST,
-            base::FormatNumber(desks_util::kMaxNumberOfDesks))};
+            base::FormatNumber(desks_util::GetMaxNumberOfDesks()))};
     ToastManager::Get()->Show(toast_data);
     return;
   }

ash/wm/overview/overview_highlight_controller_unittest.cc

@@ -884,7 +884,8 @@ TEST_P(DesksOverviewHighlightControllerTest,
     SendKey(ui::VKEY_TAB);
   }
   EXPECT_FALSE(new_desk_button->GetEnabled());
-  EXPECT_EQ(desks_util::kMaxNumberOfDesks, desks_controller->desks().size());
+  EXPECT_EQ(desks_util::GetMaxNumberOfDesks(),
+            desks_controller->desks().size());
 }
 
 TEST_P(DesksOverviewHighlightControllerTest, ZeroStateOfDesksBar) {

ash/wm/window_cycle/window_cycle_controller.cc

@@ -92,7 +92,7 @@ void ReportPossibleDesksSwitchStats(int active_desk_container_id_before_cycle) {
                active_desk_container_id_before_cycle);
   base::UmaHistogramExactLinear(kAltTabDesksSwitchDistanceHistogramName,
                                 desks_switch_distance,
-                                desks_util::kMaxNumberOfDesks);
+                                desks_util::kDesksUpperLimit);
 }
 
 }  // namespace

ash/wm/window_restore/window_restore_controller.cc

@@ -49,7 +49,7 @@ WindowRestoreController* g_instance = nullptr;
 WindowRestoreController::SaveWindowCallback g_save_window_callback_for_testing;
 
 // The list of possible app window parents.
-constexpr ShellWindowId kAppParentContainers[11] = {
+constexpr ShellWindowId kAppParentContainers[19] = {
     kShellWindowId_DefaultContainerDeprecated,
     kShellWindowId_DeskContainerB,
     kShellWindowId_DeskContainerC,
@@ -58,6 +58,14 @@ constexpr ShellWindowId kAppParentContainers[11] = {
     kShellWindowId_DeskContainerF,
     kShellWindowId_DeskContainerG,
     kShellWindowId_DeskContainerH,
+    kShellWindowId_DeskContainerI,
+    kShellWindowId_DeskContainerJ,
+    kShellWindowId_DeskContainerK,
+    kShellWindowId_DeskContainerL,
+    kShellWindowId_DeskContainerM,
+    kShellWindowId_DeskContainerN,
+    kShellWindowId_DeskContainerO,
+    kShellWindowId_DeskContainerP,
     kShellWindowId_AlwaysOnTopContainer,
     kShellWindowId_FloatContainer,
     kShellWindowId_UnparentedContainer,

chrome/browser/about_flags.cc

@@ -9729,6 +9729,9 @@ const FeatureEntry kFeatureEntries[] = {
     {"vc-controls-ui", flag_descriptions::kVcControlsUiName,
      flag_descriptions::kVcControlsUiDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(chromeos::features::kVcControlsUi)},
+    {"enable-16-desks", flag_descriptions::kDesks16Name,
+     flag_descriptions::kDesks16Description, kOsCrOS,
+     FEATURE_VALUE_TYPE(ash::features::kEnable16Desks)},
 #endif
 
     // NOTE: Adding a new flag requires adding a corresponding entry to enum

chrome/browser/flag-metadata.json

@@ -1654,6 +1654,11 @@
     "owners": [ "arakeri@microsoft.com", "flackr@chromium.org" ],
     "expiry_milestone": 99
   },
+  {
+    "name": "enable-16-desks",
+    "owners": [ "dandersson", "janetmac" ],
+    "expiry_milestone": 118
+  },
   {
     "name": "enable-accelerated-video-decode",
     "owners": [ "media-dev@chromium.org" ],

chrome/browser/flag_descriptions.cc

@@ -4993,6 +4993,10 @@ const char kDefaultLinkCapturingInBrowserDescription[] =
     "When enabled, newly installed apps will not capture links clicked in the "
     "browser.";
 
+extern const char kDesks16Name[] = "Enable up to 16 virtual desks";
+extern const char kDesks16Description[] =
+    "When enabled, up to 16 virtual desks are allowed.";
+
 const char kDesksCloseAllName[] = "Desks Close All";
 const char kDesksCloseAllDescription[] =
     "Close a desk along with all of its windows and tabs.";

chrome/browser/flag_descriptions.h

@@ -2851,6 +2851,9 @@ extern const char kCalendarModelDebugModeDescription[];
 extern const char kDefaultLinkCapturingInBrowserName[];
 extern const char kDefaultLinkCapturingInBrowserDescription[];
 
+extern const char kDesks16Name[];
+extern const char kDesks16Description[];
+
 extern const char kDesksCloseAllName[];
 extern const char kDesksCloseAllDescription[];
 

tools/metrics/histograms/enums.xml

@@ -56674,6 +56674,7 @@ from previous Chrome versions.
   <int value="-2129013032" label="DocumentTransition:enabled"/>
   <int value="-2128705444" label="AssistantAppSupport:enabled"/>
   <int value="-2128535212" label="GuestOsFiles:enabled"/>
+  <int value="-2127806304" label="Enable16Desks:disabled"/>
   <int value="-2127319228" label="enable-media-internals:disabled"/>
   <int value="-2126697213" label="EnablePalmSuppression:disabled"/>
   <int value="-2126275491" label="WebViewAppsPackageNamesAllowlist:disabled"/>
@@ -58186,6 +58187,7 @@ from previous Chrome versions.
   <int value="-1261110018" label="AllowDisableTouchpadHapticFeedback:disabled"/>
   <int value="-1260211490" label="FastPairLowPower:disabled"/>
   <int value="-1259901957" label="VrBrowserKeyboard:disabled"/>
+  <int value="-1259809702" label="Enable16Desks:enabled"/>
   <int value="-1259627326" label="AllowRepeatedUpdates:disabled"/>
   <int value="-1258141852" label="ScrollUnification:enabled"/>
   <int value="-1257822114" label="ContextMenuPopupForAllScreenSizes:disabled"/>

tools/metrics/histograms/metadata/ash/histograms.xml

@@ -1644,6 +1644,76 @@ chromium-metrics-reviews@google.com.
   </summary>
 </histogram>
 
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_10" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the tenth desk. Emitted when a desk is removed, or
+    a window is moved to another desk.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_11" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the eleventh desk. Emitted when a desk is removed,
+    or a window is moved to another desk.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_12" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the twelfth desk. Emitted when a desk is removed,
+    or a window is moved to another desk.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_13" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the thirteenth desk. Emitted when a desk is
+    removed, or a window is moved to another desk.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_14" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the fourteenth desk. Emitted when a desk is
+    removed, or a window is moved to another desk.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_15" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the fifteenth desk. Emitted when a desk is removed,
+    or a window is moved to another desk.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_16" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the sixteenth desk. Emitted when a desk is removed,
+    or a window is moved to another desk.
+  </summary>
+</histogram>
+
 <histogram name="Ash.Desks.NumberOfWindowsOnDesk_2" units="units"
     expires_after="2023-04-23">
   <owner>afakhry@chromium.org</owner>
@@ -1714,6 +1784,16 @@ chromium-metrics-reviews@google.com.
   </summary>
 </histogram>
 
+<histogram name="Ash.Desks.NumberOfWindowsOnDesk_9" units="units"
+    expires_after="2023-04-23">
+  <owner>dandersson@chromium.org</owner>
+  <owner>janetmac@chromium.org</owner>
+  <summary>
+    The number of windows on the ninth desk. Emitted when a desk is removed, or
+    a window is moved to another desk.
+  </summary>
+</histogram>
+
 <histogram name="Ash.Desks.PresentationTime.UpdateGesture" units="ms"
     expires_after="2023-01-10">
   <owner>afakhry@chromium.org</owner>