[scheduler]: Avoid waking up the scheduler to end long idle periods.

components/scheduler/child/pollable_thread_safe_flag.cc

Index: components/scheduler/child/pollable_thread_safe_flag.cc
diff --git a/components/scheduler/child/pollable_thread_safe_flag.cc b/components/scheduler/child/pollable_thread_safe_flag.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6a7e597ff436191e466792a4243ff0e328e91357
--- /dev/null
+++ b/components/scheduler/child/pollable_thread_safe_flag.cc
@@ -0,0 +1,21 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/scheduler/child/pollable_thread_safe_flag.h"
+
+PollableThreadSafeFlag::PollableThreadSafeFlag(base::Lock* write_lock_)
+    : flag_(false), write_lock_(write_lock_) {
+}
+
+PollableThreadSafeFlag::~PollableThreadSafeFlag() {
+}
+
+void PollableThreadSafeFlag::SetWhileLocked(bool value) {
+  write_lock_->AssertAcquired();
+  base::subtle::Release_Store(&flag_, value);
+}
+
+bool PollableThreadSafeFlag::IsSet() const {
+  return base::subtle::Acquire_Load(&flag_) != false;
+}