TaskScheduler: Remove base::ExecutionMode.

base/task_scheduler/task_traits.cc

Index: base/task_scheduler/task_traits.cc
diff --git a/base/task_scheduler/task_traits.cc b/base/task_scheduler/task_traits.cc
index 5bd868a330e1e5a75fa2d618d2474bc540211d4d..10cbe68efcfc4c97d14be08848ad54ba7d68ce95 100644
--- a/base/task_scheduler/task_traits.cc
+++ b/base/task_scheduler/task_traits.cc
@@ -65,19 +65,6 @@ const char* TaskShutdownBehaviorToString(
   return "";
 }
 
-const char* ExecutionModeToString(ExecutionMode execution_mode) {
-  switch (execution_mode) {
-    case ExecutionMode::PARALLEL:
-      return "PARALLEL";
-    case ExecutionMode::SEQUENCED:
-      return "SEQUENCED";
-    case ExecutionMode::SINGLE_THREADED:
-      return "SINGLE_THREADED";
-  }
-  NOTREACHED();
-  return "";
-}
-
 std::ostream& operator<<(std::ostream& os, const TaskPriority& task_priority) {
   os << TaskPriorityToString(task_priority);
   return os;
@@ -89,10 +76,4 @@ std::ostream& operator<<(std::ostream& os,
   return os;
 }
 
-std::ostream& operator<<(std::ostream& os,
-                         const ExecutionMode& execution_mode) {
-  os << ExecutionModeToString(execution_mode);
-  return os;
-}
-
 }  // namespace base