Revert of Reland: Lazily initialize MessageLoop for faster thread startup (patchset #5 id:160001 of https://codereview.chromium.org/1129953004/)

Reason for revert:
Massive data race reports, see https://crbug.com/489263

Original issue's description:
> Reland: Lazily initialize MessageLoop for faster thread startup
>
> Original review: https://codereview.chromium.org/1011683002/
>
> Reverted because it's suspected for following flakiness issues:
> http://crbug.com/485157 - Windows race
> http://crbug.com/485091 - Android ThreadWatcher
> http://crbug.com/485178 - interactive_ui_tests Menu* tests
>
> PS1 is the original patch set that gets reverted.
>
> BUG=465458, 485157, 485091, 485178
> TBR=jam
>
> Committed: https://crrev.com/8b6133a69f16702a32a3c3104630c4d9ac393b7a
> Cr-Commit-Position: refs/heads/master@{#330329}

TBR=thakis@chromium.org,toyoshim@chromium.org,jam@chromium.org,kinuko@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=465458, 485157, 485091, 485178

Review URL: https://codereview.chromium.org/1140363002

Cr-Commit-Position: refs/heads/master@{#330351}


CrOS-Libchrome-Original-Commit: 787e3347eb49a59db5e6fe0374f50464f36d48e3

1 files changed, 10 insertions, 26 deletions

diff --git a/base/message_loop/incoming_task_queue.cc b/base/message_loop/incoming_task_queue.cc
index 5e9a4613da..c1ce939b0c 100644
--- a/base/message_loop/incoming_task_queue.cc
+++ b/base/message_loop/incoming_task_queue.cc
@@ -44,8 +44,7 @@ IncomingTaskQueue::IncomingTaskQueue(MessageLoop* message_loop)
       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 @@ void IncomingTaskQueue::WillDestroyCurrentMessageLoop() {
   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 @@ bool IncomingTaskQueue::PostPendingTask(PendingTask* pending_task) {
   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