Support FileDescriptorWatcher in TaskScheduler.

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 be54614bec03fc63c555e8435cf62c529f642904..163e87a3baa50cb5e237d6dc635588d40b59db71 100644
--- a/base/task_scheduler/task_tracker.cc
+++ b/base/task_scheduler/task_tracker.cc
@@ -20,6 +20,10 @@
 #include "base/trace_event/trace_event.h"
 #include "base/values.h"
 
+#if defined(OS_POSIX) && !defined(OS_NACL_SFI)
+#include "base/files/file_descriptor_watcher_posix.h"
+#endif
+
 namespace base {
 namespace internal {
 
@@ -167,10 +171,23 @@ class TaskTracker::State {
   DISALLOW_COPY_AND_ASSIGN(State);
 };
 
-TaskTracker::TaskTracker()
+TaskTracker::TaskTracker(
+#if defined(OS_POSIX) && !defined(OS_NACL_SFI)
+    MessageLoopForIO* watch_file_descriptor_message_loop
+#endif
+    )
     : state_(new State),
       flush_cv_(flush_lock_.CreateConditionVariable()),
-      shutdown_lock_(&flush_lock_) {}
+      shutdown_lock_(&flush_lock_)
+#if defined(OS_POSIX) && !defined(OS_NACL_SFI)
+      ,
+      watch_file_descriptor_message_loop_(watch_file_descriptor_message_loop)
+#endif
+{
+#if defined(OS_POSIX) && !defined(OS_NACL_SFI)
+  DCHECK(watch_file_descriptor_message_loop_);
+#endif
+}
 TaskTracker::~TaskTracker() = default;
 
 void TaskTracker::Shutdown() {
@@ -223,6 +240,12 @@ bool TaskTracker::RunTask(std::unique_ptr<Task> task,
         TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN);
 
     {
+#if defined(OS_POSIX) && !defined(OS_NACL_SFI)
+      // Support FileDescriptorWatcher for the scope of the task.
+      FileDescriptorWatcher file_descriptor_watcher(
+          watch_file_descriptor_message_loop_);
+#endif
+
       // Set up SequenceToken as expected for the scope of the task.
       ScopedSetSequenceTokenForCurrentThread
           scoped_set_sequence_token_for_current_thread(sequence_token);