Do not inherit TaskPriority in TaskTraits.

base/task_scheduler/post_task.cc

Index: base/task_scheduler/post_task.cc
diff --git a/base/task_scheduler/post_task.cc b/base/task_scheduler/post_task.cc
index 6f9adae27f4cc3312928d773a522058761e7ea32..4de5102e19c3201af864df6903e0972648954aaf 100644
--- a/base/task_scheduler/post_task.cc
+++ b/base/task_scheduler/post_task.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/logging.h"
+#include "base/task_scheduler/scoped_set_task_priority_for_current_thread.h"
 #include "base/task_scheduler/task_scheduler.h"
 #include "base/threading/post_task_and_reply_impl.h"
 
@@ -29,6 +30,15 @@ class PostTaskAndReplyTaskRunner : public internal::PostTaskAndReplyImpl {
   const TaskTraits traits_;
 };
 
+// Returns TaskTraits based on |traits|. If TaskPriority hasn't been set
+// explicitly in |traits|, the returned TaskTraits have the current
+// TaskPriority.
+TaskTraits CreateTaskTraitsWithExplicitPriority(const TaskTraits& traits) {

[gab, 2017/04/25 17:16:41]

I prefer GetTaskTraitsWithExplicitPriority() since TaskTraits is effectively a
POD return, it's not "creating" much IMO.

[fdoray, 2017/04/25 17:57:48]

Done.

+  return traits.priority_set_explicitly()
+             ? traits
+             : TaskTraits(traits).WithPriority(
+                   internal::GetTaskPriorityForCurrentThread());
+}
 
 }  // namespace
 
@@ -62,7 +72,8 @@ void PostDelayedTaskWithTraits(const tracked_objects::Location& from_here,
   DCHECK(TaskScheduler::GetInstance())
       << "Ref. Prerequisite section of post_task.h";
   TaskScheduler::GetInstance()->PostDelayedTaskWithTraits(
-      from_here, traits, std::move(task), std::move(delay));
+      from_here, CreateTaskTraitsWithExplicitPriority(traits), std::move(task),
+      std::move(delay));
 }
 
 void PostTaskWithTraitsAndReply(const tracked_objects::Location& from_here,
@@ -76,7 +87,8 @@ void PostTaskWithTraitsAndReply(const tracked_objects::Location& from_here,
 scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits(const TaskTraits& traits) {
   DCHECK(TaskScheduler::GetInstance())
       << "Ref. Prerequisite section of post_task.h";
-  return TaskScheduler::GetInstance()->CreateTaskRunnerWithTraits(traits);
+  return TaskScheduler::GetInstance()->CreateTaskRunnerWithTraits(
+      CreateTaskTraitsWithExplicitPriority(traits));
 }
 
 scoped_refptr<SequencedTaskRunner> CreateSequencedTaskRunnerWithTraits(
@@ -84,7 +96,7 @@ scoped_refptr<SequencedTaskRunner> CreateSequencedTaskRunnerWithTraits(
   DCHECK(TaskScheduler::GetInstance())
       << "Ref. Prerequisite section of post_task.h";
   return TaskScheduler::GetInstance()->CreateSequencedTaskRunnerWithTraits(
-      traits);
+      CreateTaskTraitsWithExplicitPriority(traits));
 }
 
 scoped_refptr<SingleThreadTaskRunner> CreateSingleThreadTaskRunnerWithTraits(
@@ -92,7 +104,7 @@ scoped_refptr<SingleThreadTaskRunner> CreateSingleThreadTaskRunnerWithTraits(
   DCHECK(TaskScheduler::GetInstance())
       << "Ref. Prerequisite section of post_task.h";
   return TaskScheduler::GetInstance()->CreateSingleThreadTaskRunnerWithTraits(
-      traits);
+      CreateTaskTraitsWithExplicitPriority(traits));
 }
 
 #if defined(OS_WIN)
@@ -100,7 +112,8 @@ scoped_refptr<SingleThreadTaskRunner> CreateCOMSTATaskRunnerWithTraits(
     const TaskTraits& traits) {
   DCHECK(TaskScheduler::GetInstance())
       << "Ref. Prerequisite section of post_task.h";
-  return TaskScheduler::GetInstance()->CreateCOMSTATaskRunnerWithTraits(traits);
+  return TaskScheduler::GetInstance()->CreateCOMSTATaskRunnerWithTraits(
+      CreateTaskTraitsWithExplicitPriority(traits));
 }
 #endif  // defined(OS_WIN)