Initialize TaskScheduler in renderers.

content/renderer/render_process_impl.cc

Index: content/renderer/render_process_impl.cc
diff --git a/content/renderer/render_process_impl.cc b/content/renderer/render_process_impl.cc
index 0ad4d1b0066be8c76af12461a3d9c798bd51371a..20f71e1ed9fcf3b8e0b04ca5ed85f6041d56bb8c 100644
--- a/content/renderer/render_process_impl.cc
+++ b/content/renderer/render_process_impl.cc
@@ -12,11 +12,23 @@
 #include <mlang.h>
 #endif
 
+#include <stddef.h>
+
+#include <vector>
+
+#include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/feature_list.h"
 #include "base/sys_info.h"
+#include "base/task_scheduler/initialization_util.h"
+#include "base/task_scheduler/scheduler_worker_pool_params.h"
+#include "base/task_scheduler/task_scheduler.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/threading/platform_thread.h"
+#include "base/time/time.h"
 #include "content/child/site_isolation_stats_gatherer.h"
+#include "content/public/common/content_client.h"
 #include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/renderer/content_renderer_client.h"
@@ -25,6 +37,14 @@
 
 namespace {
 
+enum WorkerPoolType : size_t {
+  BACKGROUND = 0,
+  BACKGROUND_FILE_IO,
+  FOREGROUND,
+  FOREGROUND_FILE_IO,
+  WORKER_POOL_COUNT  // Always last.
+};
+
 const base::Feature kV8_ES2015_TailCalls_Feature {
   "V8_ES2015_TailCalls", base::FEATURE_DISABLED_BY_DEFAULT
 };
@@ -50,6 +70,84 @@ void SetV8FlagIfHasSwitch(const char* switch_name, const char* v8_flag) {
   }
 }
 
+std::vector<base::SchedulerWorkerPoolParams>
+GetDefaultSchedulerWorkerPoolParams() {
+  using StandbyThreadPolicy =
+      base::SchedulerWorkerPoolParams::StandbyThreadPolicy;
+  using ThreadPriority = base::ThreadPriority;
+  constexpr size_t kMaxNumThreadsInBackgroundPool = 1;
+  constexpr size_t kMaxNumThreadsInBackgroundFileIOPool = 1;
+  constexpr int kMaxNumThreadsInForegroundPoolLowerBound = 2;
+  constexpr int kMaxNumThreadsInForegroundPoolUpperBound = 4;
+  constexpr double kMaxNumThreadsInForegroundPoolCoresMultiplier = 1;
+  constexpr int kMaxNumThreadsInForegroundPoolOffset = 0;
+  constexpr size_t kMaxNumThreadsInForegroundFileIOPool = 1;
+  constexpr auto kSuggestedReclaimTime = base::TimeDelta::FromSeconds(30);
+
+  std::vector<base::SchedulerWorkerPoolParams> params_vector;
+  params_vector.emplace_back("RendererBackground", ThreadPriority::BACKGROUND,
+                             StandbyThreadPolicy::LAZY,
+                             kMaxNumThreadsInBackgroundPool,
+                             kSuggestedReclaimTime);
+  params_vector.emplace_back(
+      "RendererBackgroundFileIO", ThreadPriority::BACKGROUND,
+      StandbyThreadPolicy::LAZY, kMaxNumThreadsInBackgroundFileIOPool,
+      kSuggestedReclaimTime);
+  params_vector.emplace_back("RendererForeground", ThreadPriority::NORMAL,
+                             StandbyThreadPolicy::LAZY,
+                             base::RecommendedMaxNumberOfThreadsInPool(
+                                 kMaxNumThreadsInForegroundPoolLowerBound,
+                                 kMaxNumThreadsInForegroundPoolUpperBound,
+                                 kMaxNumThreadsInForegroundPoolCoresMultiplier,
+                                 kMaxNumThreadsInForegroundPoolOffset),
+                             kSuggestedReclaimTime);
+  params_vector.emplace_back("RendererForegroundFileIO", ThreadPriority::NORMAL,
+                             StandbyThreadPolicy::LAZY,
+                             kMaxNumThreadsInForegroundFileIOPool,
+                             kSuggestedReclaimTime);
+  DCHECK_EQ(WORKER_POOL_COUNT, params_vector.size());
+  return params_vector;
+}
+
+// Returns the worker pool index for |traits| defaulting to FOREGROUND or
+// FOREGROUND_FILE_IO on any other priorities based off of worker pools defined
+// in GetDefaultSchedulerWorkerPoolParams().
+size_t DefaultRendererWorkerPoolIndexForTraits(const base::TaskTraits& traits) {
+  const bool is_background =
+      traits.priority() == base::TaskPriority::BACKGROUND;
+  if (traits.with_file_io())
+    return is_background ? BACKGROUND_FILE_IO : FOREGROUND_FILE_IO;
+
+  return is_background ? BACKGROUND : FOREGROUND;
+}
+
+void InitializeTaskScheduler() {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kSingleProcess)) {
+    // There should already be a TaskScheduler when the renderer runs inside the
+    // browser process.
+    DCHECK(base::TaskScheduler::GetInstance());
+    return;
+  }
+  DCHECK(!base::TaskScheduler::GetInstance());
+
+  std::vector<base::SchedulerWorkerPoolParams> params_vector;
+  base::TaskScheduler::WorkerPoolIndexForTraitsCallback
+      index_to_traits_callback;
+  content::GetContentClient()->renderer()->GetTaskSchedulerInitializationParams(
+      &params_vector, &index_to_traits_callback);
+
+  if (params_vector.empty()) {
+    params_vector = GetDefaultSchedulerWorkerPoolParams();
+    index_to_traits_callback =
+        base::Bind(&DefaultRendererWorkerPoolIndexForTraits);
+  }
+  DCHECK(index_to_traits_callback);
+
+  base::TaskScheduler::CreateAndSetDefaultTaskScheduler(
+      params_vector, index_to_traits_callback);
+}
+
 }  // namespace
 
 namespace content {
@@ -103,6 +201,8 @@ RenderProcessImpl::RenderProcessImpl()
 
   SiteIsolationStatsGatherer::SetEnabled(
       GetContentClient()->renderer()->ShouldGatherSiteIsolationStats());
+
+  InitializeTaskScheduler();
 }
 
 RenderProcessImpl::~RenderProcessImpl() {
@@ -112,6 +212,12 @@ RenderProcessImpl::~RenderProcessImpl() {
     DLOG(ERROR) << "WebFrame LEAKED " << count << " TIMES";
 #endif
 
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kSingleProcess)) {
+    DCHECK(base::TaskScheduler::GetInstance());
+    base::TaskScheduler::GetInstance()->Shutdown();
+  }
+
   GetShutDownEvent()->Signal();
 }