Add TaskTraits::MayBlock and TaskTraits::WithSyncPrimitives.

base/task_scheduler/task_tracker.cc

Index: base/task_scheduler/task_tracker.cc
diff --git a/base/task_scheduler/task_tracker.cc b/base/task_scheduler/task_tracker.cc
index 4c1ee8da3dd285ea1f668cab15b4f4565e91059e..87b75b45a0bfece5a4e0bce46ec0891692e02185 100644
--- a/base/task_scheduler/task_tracker.cc
+++ b/base/task_scheduler/task_tracker.cc
@@ -225,9 +225,9 @@ bool TaskTracker::RunTask(std::unique_ptr<Task> task,
             task->traits.shutdown_behavior() !=
             TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN);
     const bool previous_io_allowed =
-        ThreadRestrictions::SetIOAllowed(task->traits.with_file_io());
+        ThreadRestrictions::SetIOAllowed(task->traits.may_block());
     const bool previous_wait_allowed =

[robliao, 2016/12/19 22:04:56]

Rename this while we're here.

[fdoray, 2016/12/20 13:32:24]

This variable still contains the previous value of the "wait allowed" thread
restriction. I plan to rename ThreadRestrictions::SetWaitAllowed and this
variable in a separate CL.

-        ThreadRestrictions::SetWaitAllowed(task->traits.with_wait());
+        ThreadRestrictions::SetWaitAllowed(task->traits.with_sync_primitives());
 
     {
       ScopedSetSequenceTokenForCurrentThread