MessageLoop mischief

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index 72185a8e11a3d085d43af4b131f26cbd87a09490..f48a8dcd9fee751b042bc63e8040441a70ec8743 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -390,15 +390,26 @@ bool MessageLoop::ProcessNextDelayedNonNestableTask() {
   if (run_loop_->run_depth_ != 1)
     return false;
 
-  if (deferred_non_nestable_work_queue_.empty())
-    return false;
+  while (!deferred_non_nestable_work_queue_.empty()) {
+    PendingTask pending_task =
+        std::move(deferred_non_nestable_work_queue_.front());
+    deferred_non_nestable_work_queue_.pop();
 
-  PendingTask pending_task =
-      std::move(deferred_non_nestable_work_queue_.front());
-  deferred_non_nestable_work_queue_.pop();
+    if (pending_task.task.IsCancelled()) {
+#if defined(OS_WIN)
+      if (pending_task.is_high_res) {
+        pending_high_res_tasks_--;
+        CHECK_GE(pending_high_res_tasks_, 0);
+      }
+#endif
+      continue;
+    }
 
-  RunTask(&pending_task);
-  return true;
+    RunTask(&pending_task);
+    return true;
+  }
+
+  return false;
 }
 
 void MessageLoop::RunTask(PendingTask* pending_task) {
@@ -444,6 +455,28 @@ void MessageLoop::AddToDelayedWorkQueue(PendingTask pending_task) {
   delayed_work_queue_.push(std::move(pending_task));
 }
 
+bool MessageLoop::SweepDelayedWorkQueue() {
+  DCHECK(!delayed_work_queue_.empty());
+
+  do {
+    const auto& pending_task = delayed_work_queue_.top();
+    if (pending_task.task.IsCancelled()) {
+#if defined(OS_WIN)
+      if (pending_task.is_high_res) {
+        pending_high_res_tasks_--;
+        CHECK_GE(pending_high_res_tasks_, 0);
+      }
+#endif
+      delayed_work_queue_.pop();
+      continue;
+    } else {
+      return false;
+    }
+  } while (!delayed_work_queue_.empty());
+
+  return true;
+}
+
 bool MessageLoop::DeletePendingTasks() {
   bool did_work = !work_queue_.empty();
   while (!work_queue_.empty()) {
@@ -512,6 +545,17 @@ bool MessageLoop::DoWork() {
     do {
       PendingTask pending_task = std::move(work_queue_.front());
       work_queue_.pop();
+
+      if (pending_task.task.IsCancelled()) {
+#if defined(OS_WIN)
+        if (pending_task.is_high_res) {
+          pending_high_res_tasks_--;
+          CHECK_GE(pending_high_res_tasks_, 0);
+        }
+#endif
+        continue;
+      }
+
       if (!pending_task.delayed_run_time.is_null()) {
         int sequence_num = pending_task.sequence_num;
         TimeTicks delayed_run_time = pending_task.delayed_run_time;
@@ -531,7 +575,8 @@ bool MessageLoop::DoWork() {
 }
 
 bool MessageLoop::DoDelayedWork(TimeTicks* next_delayed_work_time) {
-  if (!nestable_tasks_allowed_ || delayed_work_queue_.empty()) {
+  if (!nestable_tasks_allowed_ || delayed_work_queue_.empty() ||
+      SweepDelayedWorkQueue()) {
     recent_time_ = *next_delayed_work_time = TimeTicks();
     return false;
   }
@@ -556,10 +601,12 @@ bool MessageLoop::DoDelayedWork(TimeTicks* next_delayed_work_time) {
       std::move(const_cast<PendingTask&>(delayed_work_queue_.top()));
   delayed_work_queue_.pop();
 
-  if (!delayed_work_queue_.empty())
+  bool did_work = DeferOrRunPendingTask(std::move(pending_task));
+
+  if (!delayed_work_queue_.empty() && !SweepDelayedWorkQueue())
     *next_delayed_work_time = delayed_work_queue_.top().delayed_run_time;
 
-  return DeferOrRunPendingTask(std::move(pending_task));
+  return did_work;
 }
 
 bool MessageLoop::DoIdleWork() {