Revert of Fix Windows logoff race.

chrome/browser/browser_process_impl.cc

Index: chrome/browser/browser_process_impl.cc
diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index e014c1803ea454929ce339613e4ed93614a111b5..a36ac9fa8ed0e36a3cdbc28cb6ed078173008095 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -8,7 +8,6 @@
 #include <map>
 #include <vector>
 
-#include "base/atomic_ref_count.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ -316,6 +315,12 @@
   io_thread_.reset();
 }
 
+#if defined(USE_X11) || defined(OS_WIN)
+static void Signal(base::WaitableEvent* event) {
+  event->Signal();
+}
+#endif
+
 unsigned int BrowserProcessImpl::AddRefModule() {
   DCHECK(CalledOnValidThread());
 
@@ -379,81 +384,12 @@
   return module_ref_count_;
 }
 
-namespace {
-
-// Used at the end of session to block the UI thread for completion of sentinel
-// tasks on the set of threads used to persist profile data and local state.
-// This is done to ensure that the data has been persisted to disk before
-// continuing.
-class RundownTaskCounter :
-    public base::RefCountedThreadSafe<RundownTaskCounter> {
- public:
-  RundownTaskCounter();
-
-  // Posts a rundown task to |task_runner|, can be invoked an arbitrary number
-  // of times before calling TimedWait.
-  void Post(base::SequencedTaskRunner* task_runner);
-
-  // Waits until the count is zero or |max_time| has passed.
-  // This can only be called once per instance.
-  bool TimedWait(const base::TimeDelta& max_time);
-
- private:
-  friend class base::RefCountedThreadSafe<RundownTaskCounter>;
-  ~RundownTaskCounter() {}
-
-  // Decrements the counter and releases the waitable event on transition to
-  // zero.
-  void Decrement();
-
-  // The count starts at one to defer the possibility of one->zero transitions
-  // until TimedWait is called.
-  base::AtomicRefCount count_;
-  base::WaitableEvent waitable_event_;
-
-  DISALLOW_COPY_AND_ASSIGN(RundownTaskCounter);
-};
-
-RundownTaskCounter::RundownTaskCounter()
-    : count_(1), waitable_event_(true, false) {
-}
-
-void RundownTaskCounter::Post(base::SequencedTaskRunner* task_runner) {
-  // As the count starts off at one, it should never get to zero unless
-  // TimedWait has been called.
-  DCHECK(!base::AtomicRefCountIsZero(&count_));
-
-  base::AtomicRefCountInc(&count_);
-
-  task_runner->PostTask(FROM_HERE,
-      base::Bind(&RundownTaskCounter::Decrement, this));
-}
-
-void RundownTaskCounter::Decrement() {
-  if (!base::AtomicRefCountDec(&count_))
-    waitable_event_.Signal();
-}
-
-bool RundownTaskCounter::TimedWait(const base::TimeDelta& max_time) {
-  // Decrement the excess count from the constructor.
-  Decrement();
-
-  return waitable_event_.TimedWait(max_time);
-}
-
-}  // namespace
-
 void BrowserProcessImpl::EndSession() {
   // Mark all the profiles as clean.
   ProfileManager* pm = profile_manager();
   std::vector<Profile*> profiles(pm->GetLoadedProfiles());
-  scoped_refptr<RundownTaskCounter> rundown_counter(new RundownTaskCounter());
-  for (size_t i = 0; i < profiles.size(); ++i) {
-    Profile* profile = profiles[i];
-    profile->SetExitType(Profile::EXIT_SESSION_ENDED);
-
-    rundown_counter->Post(profile->GetIOTaskRunner());
-  }
+  for (size_t i = 0; i < profiles.size(); ++i)
+    profiles[i]->SetExitType(Profile::EXIT_SESSION_ENDED);
 
   // Tell the metrics service it was cleanly shutdown.
   MetricsService* metrics = g_browser_process->metrics_service();
@@ -464,8 +400,6 @@
     // On ChromeOS, chrome gets killed when hangs, so no need to
     // commit metrics::prefs::kStabilitySessionEndCompleted change immediately.
     local_state()->CommitPendingWrite();
-
-    rundown_counter->Post(local_state_task_runner_);
 #endif
   }
 
@@ -476,9 +410,7 @@
   // otherwise on startup we'll think we crashed. So we block until done and
   // then proceed with normal shutdown.
 #if defined(USE_X11) || defined(OS_WIN)
-  // Do a best-effort wait on the successful countdown of rundown tasks. Note
-  // that if we don't complete "quickly enough", Windows will terminate our
-  // process.
+  // Create a waitable event to block on file writing being complete.
   //
   // On Windows, we previously posted a message to FILE and then ran a nested
   // message loop, waiting for that message to be processed until quitting.
@@ -489,8 +421,16 @@
   // GPU process synchronously. Because the system may not be allowing
   // processes to launch, this can result in a hang. See
   // http://crbug.com/318527.
-  rundown_counter->TimedWait(
-      base::TimeDelta::FromSeconds(kEndSessionTimeoutSeconds));
+  scoped_ptr<base::WaitableEvent> done_writing(
+      new base::WaitableEvent(false, false));
+  BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
+      base::Bind(Signal, done_writing.get()));
+  // If all file writes haven't cleared in the timeout, leak the WaitableEvent
+  // so that there's no race to reference it in Signal().
+  if (!done_writing->TimedWait(
+      base::TimeDelta::FromSeconds(kEndSessionTimeoutSeconds))) {
+    ignore_result(done_writing.release());
+  }
 #else
   NOTIMPLEMENTED();
 #endif