Add TaskScheduler::InitParams and accept it in TaskSchedulerImpl constructor.

base/task_scheduler/scheduler_worker_pool_params.cc

Index: base/task_scheduler/scheduler_worker_pool_params.cc
diff --git a/base/task_scheduler/scheduler_worker_pool_params.cc b/base/task_scheduler/scheduler_worker_pool_params.cc
index 43a66d0f87f9208324ed9f34153cd4e7621bc0a3..316aa536248303937d6749df8a67ed4787dbb740 100644
--- a/base/task_scheduler/scheduler_worker_pool_params.cc
+++ b/base/task_scheduler/scheduler_worker_pool_params.cc
@@ -4,6 +4,8 @@
 
 #include "base/task_scheduler/scheduler_worker_pool_params.h"
 
+#include "base/strings/string_util.h"
+
 namespace base {
 
 SchedulerWorkerPoolParams::SchedulerWorkerPoolParams(
@@ -21,6 +23,18 @@ SchedulerWorkerPoolParams::SchedulerWorkerPoolParams(
       backward_compatibility_(backward_compatibility) {}
 
 SchedulerWorkerPoolParams::SchedulerWorkerPoolParams(
+    StandbyThreadPolicy standby_thread_policy,
+    int max_threads,
+    TimeDelta suggested_reclaim_time,
+    SchedulerBackwardCompatibility backward_compatibility)
+    : SchedulerWorkerPoolParams(EmptyString(),

[gab, 2017/03/20 20:31:56]

s/EmptyString()/std::string()/

(first time I see base::EmptyString() and its meta comment leads me to believe
it's not meant for this either)

[fdoray, 2017/03/20 20:43:53]

Done.

+                                ThreadPriority::NORMAL,
+                                standby_thread_policy,
+                                max_threads,
+                                suggested_reclaim_time,
+                                backward_compatibility) {}
+
+SchedulerWorkerPoolParams::SchedulerWorkerPoolParams(
     const SchedulerWorkerPoolParams& other) = default;
 
 SchedulerWorkerPoolParams& SchedulerWorkerPoolParams::operator=(