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..1b7a64eac4ffe5895688f296eb4a606a134667be 100644
--- a/content/renderer/render_process_impl.cc
+++ b/content/renderer/render_process_impl.cc
@@ -12,10 +12,17 @@
 #include <mlang.h>
 #endif
 
+#include <stddef.h>
+
+#include <vector>
+
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/feature_list.h"
 #include "base/sys_info.h"
+#include "base/task_scheduler/scheduler_worker_pool_params.h"
+#include "base/task_scheduler/task_scheduler.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "content/child/site_isolation_stats_gatherer.h"
 #include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
@@ -23,6 +30,10 @@
 #include "third_party/WebKit/public/web/WebFrame.h"
 #include "v8/include/v8.h"
 
+namespace base {
+class TaskTraits;
+}
+
 namespace {
 
 const base::Feature kV8_ES2015_TailCalls_Feature {
@@ -50,12 +61,39 @@ void SetV8FlagIfHasSwitch(const char* switch_name, const char* v8_flag) {
   }
 }
 
+bool MaybeInitializeTaskScheduler() {

[robliao, 2016/11/14 16:05:26]

What's the behavior when base linked to chrome.dll and chrome_child.dll?
How do we access chrome.dll's task scheduler?

[gab, 2016/11/14 16:16:43]

Hmm? base is linked to both but any process instance is only running one or the
other? Is there a case of running both chrome.dll and chrome_child.dll in the
same process? single-process mode I guess? Then maybe the code below is
incorrect for single-process mode?

[fdoray, 2016/11/15 16:30:34]

--single-process only works in component builds
https://cs.chromium.org/chromium/src/content/app/content_main_runner.cc?sq=pa...
, so it is not possible to have a process that loads chrome.dll and
chrome_child.dll.

+  // TaskScheduler already exists when the renderer runs inside the browser
+  // process.
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(

[gab, 2016/11/14 16:16:43]

Use base::TaskScheduler::GetInstance() instead? (potentially covers other cases
we're not aware of?)

Although we probably want to know if there are more cases so maybe:

if (...GetInstance()) { 
  // TaskScheduler is not expected to already exist unless in single process
mode.
  DCHECK(..single process..); 
  return false; 
}

Note: this also allows TaskScheduler to be live in renderers and not in browser
if we ever care.

[fdoray, 2016/11/15 16:30:34]

Done. With some changes because I don't want a RenderProcessImpl to initialize a
TaskScheduler and enable SequencedWorkerPool redirection in the browser process
(otherwise, the browser process starts without a TaskScheduler and gets one when
it launches a renderer...).

+          switches::kSingleProcess)) {
+    return false;
+  }
+
+  std::vector<base::SchedulerWorkerPoolParams> worker_pool_params_vector;
+  base::Callback<size_t(const base::TaskTraits& traits)>
+      worker_pool_index_for_traits_callback;
+  bool should_redirect_sequenced_worker_pool = false;
+
+  if (!content::GetContentClient()->renderer()->ShouldInitializeTaskScheduler(
+          &worker_pool_params_vector, &worker_pool_index_for_traits_callback,
+          &should_redirect_sequenced_worker_pool)) {
+    return false;
+  }
+
+  base::TaskScheduler::CreateAndSetDefaultTaskScheduler(
+      worker_pool_params_vector, worker_pool_index_for_traits_callback);
+
+  if (should_redirect_sequenced_worker_pool)
+    base::SequencedWorkerPool::RedirectToTaskSchedulerForProcess();
+
+  return true;
+}
+
 }  // namespace
 
 namespace content {
 
-RenderProcessImpl::RenderProcessImpl()
-    : enabled_bindings_(0) {
+RenderProcessImpl::RenderProcessImpl() {
 #if defined(OS_WIN)
   // HACK:  See http://b/issue?id=1024307 for rationale.
   if (GetModuleHandle(L"LPK.DLL") == NULL) {
@@ -103,6 +141,8 @@ RenderProcessImpl::RenderProcessImpl()
 
   SiteIsolationStatsGatherer::SetEnabled(
       GetContentClient()->renderer()->ShouldGatherSiteIsolationStats());
+
+  initialized_task_scheduler_ = MaybeInitializeTaskScheduler();
 }
 
 RenderProcessImpl::~RenderProcessImpl() {
@@ -112,6 +152,11 @@ RenderProcessImpl::~RenderProcessImpl() {
     DLOG(ERROR) << "WebFrame LEAKED " << count << " TIMES";
 #endif
 
+  if (initialized_task_scheduler_) {
+    DCHECK(base::TaskScheduler::GetInstance());
+    base::TaskScheduler::GetInstance()->Shutdown();
+  }
+
   GetShutDownEvent()->Signal();
 }