Increase the number of TaskScheduler foreground threads 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 db042b903f1748a8b4ff9fbb4e92f0b3bb048555..d74a95f1df616f61db3294914bac58c08aaa279a 100644
--- a/content/renderer/render_process_impl.cc
+++ b/content/renderer/render_process_impl.cc
@@ -93,7 +93,6 @@ GetDefaultSchedulerWorkerPoolParams() {
   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;
@@ -113,9 +112,14 @@ GetDefaultSchedulerWorkerPoolParams() {
                                  kMaxNumThreadsInForegroundPoolCoresMultiplier,
                                  kMaxNumThreadsInForegroundPoolOffset),
                              kSuggestedReclaimTime);
+
+  // V8Platform::CallOnBackgroundThread() posts foreground blocking tasks. It
+  // expects to have as many threads as cores available for these tasks.

[gab, 2017/02/06 21:17:10]

Such a comment is fine to justify CL (i.e. in desc) but doesn't belong in this
top-level code IMO.

Also, why are these blocking? Blocking + flooding cores with work doesn't
typically go together?

[fdoray, 2017/02/09 13:32:13]

Done. The v8 tasks are only blocking in tests.

+  const int max_num_foreground_file_io_threads =

[gab, 2017/02/06 21:17:10]

s/file_io/blocking/ now

[fdoray, 2017/02/09 13:32:14]

Taken care of in a separate CL https://codereview.chromium.org/2625213003/

+      std::max(2, base::SysInfo::NumberOfProcessors());
   params_vector.emplace_back("RendererForegroundFileIO", ThreadPriority::NORMAL,
                              StandbyThreadPolicy::LAZY,
-                             kMaxNumThreadsInForegroundFileIOPool,
+                             max_num_foreground_file_io_threads,
                              kSuggestedReclaimTime);
   DCHECK_EQ(WORKER_POOL_COUNT, params_vector.size());
   return params_vector;