[Cleanup] Remove DifferentWorkQueueCapacities experiment code

No good metric movements.

Bug: 1347892
Change-Id: Ibac003d725e2b8806eea1dd1c5c3394c0d37ba18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4181491
Commit-Queue: Peilin Wang <peilinwang@google.com>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1095067}

base/feature_list.cc

@@ -27,7 +27,6 @@
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
-#include "base/task/sequence_manager/work_queue.h"
 #include "build/build_config.h"
 
 namespace base {
@@ -590,8 +589,6 @@ void FeatureList::SetInstance(std::unique_ptr<FeatureList> instance) {
   g_cache_override_state =
       base::FeatureList::IsEnabled(kCacheFeatureOverrideState);
 
-  base::sequence_manager::internal::WorkQueue::ConfigureCapacityFieldTrial();
-
 #if BUILDFLAG(DCHECK_IS_CONFIGURABLE)
   // Update the behaviour of LOGGING_DCHECK to match the Feature configuration.
   // DCHECK is also forced to be FATAL if we are running a death-test.

base/task/sequence_manager/work_queue.cc

@@ -4,8 +4,6 @@
 
 #include "base/task/sequence_manager/work_queue.h"
 
-#include <atomic>
-
 #include "base/containers/stack_container.h"
 #include "base/debug/alias.h"
 #include "base/metrics/field_trial_params.h"
@@ -20,40 +18,6 @@ namespace base {
 namespace sequence_manager {
 namespace internal {
 
-namespace {
-
-BASE_FEATURE(kDifferentWorkQueueCapacities,
-             "DifferentWorkQueueCapacities",
-             FEATURE_DISABLED_BY_DEFAULT);
-
-std::atomic<bool> g_different_work_queue_capacities_feature_enabled(false);
-
-}  // namespace
-
-// static
-void WorkQueue::ConfigureCapacityFieldTrial() {
-  g_different_work_queue_capacities_feature_enabled.store(
-      FeatureList::IsEnabled(kDifferentWorkQueueCapacities),
-      std::memory_order_relaxed);
-}
-
-// static
-bool WorkQueue::IsDifferentWorkQueueCapacitiesEnabled() {
-  return g_different_work_queue_capacities_feature_enabled.load(
-      std::memory_order_relaxed);
-}
-
-// static
-size_t WorkQueue::GetStackCapacityChoice() {
-  static const size_t kStackCapacityChoice =
-      IsDifferentWorkQueueCapacitiesEnabled()
-          ? static_cast<size_t>(GetFieldTrialParamByFeatureAsInt(
-                kDifferentWorkQueueCapacities, "StackCapacity",
-                StackCapacity::kDefault))
-          : StackCapacity::kDefault;
-  return kStackCapacityChoice;
-}
-
 WorkQueue::WorkQueue(TaskQueueImpl* task_queue,
                      const char* name,
                      QueueType queue_type)
@@ -256,12 +220,15 @@ Task WorkQueue::TakeTaskFromWorkQueue() {
   return pending_task;
 }
 
-template <size_t stack_capacity>
-bool WorkQueue::RemoveAllCancelledTasksFromFrontImpl() {
+bool WorkQueue::RemoveAllCanceledTasksFromFront() {
+  if (!work_queue_sets_) {
+    return false;
+  }
+
   // Since task destructors could have a side-effect of deleting this task queue
   // we move cancelled tasks into a temporary container which can be emptied
   // without accessing |this|.
-  StackVector<Task, stack_capacity> tasks_to_delete;
+  StackVector<Task, 8> tasks_to_delete;
 
   while (!tasks_.empty()) {
     const auto& pending_task = tasks_.front();
@@ -291,31 +258,6 @@ bool WorkQueue::RemoveAllCancelledTasksFromFrontImpl() {
   return !tasks_to_delete->empty();
 }
 
-template bool WorkQueue::RemoveAllCancelledTasksFromFrontImpl<
-    WorkQueue::StackCapacity::kSmall>();
-template bool WorkQueue::RemoveAllCancelledTasksFromFrontImpl<
-    WorkQueue::StackCapacity::kMedium>();
-template bool WorkQueue::RemoveAllCancelledTasksFromFrontImpl<
-    WorkQueue::StackCapacity::kLarge>();
-template bool WorkQueue::RemoveAllCancelledTasksFromFrontImpl<
-    WorkQueue::StackCapacity::kDefault>();
-
-bool WorkQueue::RemoveAllCanceledTasksFromFront() {
-  if (!work_queue_sets_)
-    return false;
-
-  switch (GetStackCapacityChoice()) {
-    case StackCapacity::kSmall:
-      return RemoveAllCancelledTasksFromFrontImpl<StackCapacity::kSmall>();
-    case StackCapacity::kMedium:
-      return RemoveAllCancelledTasksFromFrontImpl<StackCapacity::kMedium>();
-    case StackCapacity::kLarge:
-      return RemoveAllCancelledTasksFromFrontImpl<StackCapacity::kLarge>();
-    default:
-      return RemoveAllCancelledTasksFromFrontImpl<StackCapacity::kDefault>();
-  }
-}
-
 void WorkQueue::AssignToWorkQueueSets(WorkQueueSets* work_queue_sets) {
   work_queue_sets_ = work_queue_sets;
 }

base/task/sequence_manager/work_queue.h

@@ -163,27 +163,6 @@ class BASE_EXPORT WorkQueue {
   void CollectTasksOlderThan(TaskOrder reference,
                              std::vector<const Task*>* result) const;
 
-  // This is for an experiment where we try different WorkQueue capacities
-  // when deleting tasks in RemoveAllCanceledTasksFromFront() (see
-  // crbug.com/1347892). Tests spawn threads around the time FeatureList is
-  // initialized, which creates race conditions as WorkQueue is trying to read
-  // the Feature while threads spawn. To solve this, we store the value of the
-  // Feature in a std::atomic<bool> and initialize it once in SetInstance(), and
-  // read this atomic value instead of calling IsEnabled().
-  static void ConfigureCapacityFieldTrial();
-  static bool IsDifferentWorkQueueCapacitiesEnabled();
-
- private:
-  enum StackCapacity : size_t {
-    kSmall = 4,
-    kMedium = 16,
-    kLarge = 24,
-    kDefault = 8,
-  };
-
-  static size_t GetStackCapacityChoice();
-
-  template <size_t stack_capacity>
   bool RemoveAllCancelledTasksFromFrontImpl();
 
   bool InsertFenceImpl(Fence fence);

testing/variations/fieldtrial_testing_config.json

@@ -4062,24 +4062,6 @@
             ]
         }
     ],
-    "DifferentWorkQueueCapacities": [
-        {
-            "platforms": [
-                "android"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "params": {
-                        "StackCapacity": "24"
-                    },
-                    "enable_features": [
-                        "DifferentWorkQueueCapacities"
-                    ]
-                }
-            ]
-        }
-    ],
     "DisableGles2ForOopR": [
         {
             "platforms": [