Revert of Reland: Lazily initialize MessageLoop for faster thread startup

base/message_loop/incoming_task_queue.cc

Index: base/message_loop/incoming_task_queue.cc
diff --git a/base/message_loop/incoming_task_queue.cc b/base/message_loop/incoming_task_queue.cc
index 5e9a4613da1cad2a28369aa78b69e87001ad9e9f..c1ce939b0c4708ac431d80b54a35ee8ef73b314c 100644
--- a/base/message_loop/incoming_task_queue.cc
+++ b/base/message_loop/incoming_task_queue.cc
@@ -44,8 +44,7 @@
       message_loop_(message_loop),
       next_sequence_num_(0),
       message_loop_scheduled_(false),
-      always_schedule_work_(AlwaysNotifyPump(message_loop_->type())),
-      is_ready_for_scheduling_(false) {
+      always_schedule_work_(AlwaysNotifyPump(message_loop_->type())) {
 }
 
 bool IncomingTaskQueue::AddToIncomingQueue(
@@ -110,15 +109,6 @@
   message_loop_ = NULL;
 }
 
-void IncomingTaskQueue::StartScheduling() {
-  AutoLock lock(incoming_queue_lock_);
-  DCHECK(!is_ready_for_scheduling_);
-  DCHECK(!message_loop_scheduled_);
-  is_ready_for_scheduling_ = true;
-  if (!incoming_queue_.empty())
-    ScheduleWork();
-}
-
 IncomingTaskQueue::~IncomingTaskQueue() {
   // Verify that WillDestroyCurrentMessageLoop() has been called.
   DCHECK(!message_loop_);
@@ -158,25 +148,19 @@
   incoming_queue_.push(*pending_task);
   pending_task->task.Reset();
 
-  if (is_ready_for_scheduling_ &&
-      (always_schedule_work_ || (!message_loop_scheduled_ && was_empty))) {
-    ScheduleWork();
+  if (always_schedule_work_ || (!message_loop_scheduled_ && was_empty)) {
+    // Wake up the message loop.
+    message_loop_->ScheduleWork();
+    // After we've scheduled the message loop, we do not need to do so again
+    // until we know it has processed all of the work in our queue and is
+    // waiting for more work again. The message loop will always attempt to
+    // reload from the incoming queue before waiting again so we clear this flag
+    // in ReloadWorkQueue().
+    message_loop_scheduled_ = true;
   }
 
   return true;
 }
 
-void IncomingTaskQueue::ScheduleWork() {
-  DCHECK(is_ready_for_scheduling_);
-  // Wake up the message loop.
-  message_loop_->ScheduleWork();
-  // After we've scheduled the message loop, we do not need to do so again
-  // until we know it has processed all of the work in our queue and is
-  // waiting for more work again. The message loop will always attempt to
-  // reload from the incoming queue before waiting again so we clear this flag
-  // in ReloadWorkQueue().
-  message_loop_scheduled_ = true;
-}
-
 }  // namespace internal
 }  // namespace base