[Reland] Per WebViewScheduler virtual time

components/scheduler/base/task_queue_manager.cc

Index: components/scheduler/base/task_queue_manager.cc
diff --git a/components/scheduler/base/task_queue_manager.cc b/components/scheduler/base/task_queue_manager.cc
index 584eb703646e0173c5e79b748993e49a56760677..19c0209a89efbd9e5a2ad82905aed1986cb1f6ae 100644
--- a/components/scheduler/base/task_queue_manager.cc
+++ b/components/scheduler/base/task_queue_manager.cc
@@ -48,6 +48,7 @@ TaskQueueManager::TaskQueueManager(
           disabled_by_default_tracing_category),
       disabled_by_default_verbose_tracing_category_(
           disabled_by_default_verbose_tracing_category),
+      current_selected_task_queue_(nullptr),
       observer_(nullptr),
       deletion_sentinel_(new DeletionSentinel()),
       weak_factory_(this) {
@@ -218,12 +219,8 @@ void TaskQueueManager::DoWork(base::TimeTicks run_time, bool from_main_thread) {
   // TODO(alexclarke): Consider refactoring the above loop to terminate only
   // when there's no more work left to be done, rather than posting a
   // continuation task.
-  if (!selector_.EnabledWorkQueuesEmpty() || TryAdvanceTimeDomains()) {
+  if (!selector_.EnabledWorkQueuesEmpty() || TryAdvanceTimeDomains())
     MaybeScheduleImmediateWork(FROM_HERE);
-  } else {
-    // Tell the task runner we have no more work.
-    delegate_->OnNoMoreImmediateWork();
-  }
 }
 
 bool TaskQueueManager::TryAdvanceTimeDomains() {
@@ -280,7 +277,11 @@ TaskQueueManager::ProcessTaskResult TaskQueueManager::ProcessTaskFromWorkQueue(
   }
   TRACE_EVENT1(tracing_category_,
                "TaskQueueManager::RunTask", "queue", queue->GetName());
+  internal::TaskQueueImpl* prev_selected_task_queue =
+      current_selected_task_queue_;
+  current_selected_task_queue_ = queue;
   task_annotator_.RunTask("TaskQueueManager::PostTask", pending_task);
+  current_selected_task_queue_ = prev_selected_task_queue;

[Sami, 2016/02/01 11:15:06]

Should we guard against prev_selected_task_queue getting deleted by this task?

[alex clarke (OOO till 29th), 2016/02/01 14:16:54]

Done.

 
   // Detect if the TaskQueueManager just got deleted.  If this happens we must
   // not access any member variables after this point.