Flush SequenceWorkerPool tasks after each unit test.

base/test/task_runner_test_template.cc

Index: base/test/task_runner_test_template.cc
===================================================================
--- base/test/task_runner_test_template.cc	(revision 178148)
+++ base/test/task_runner_test_template.cc	(working copy)
@@ -8,7 +8,7 @@
 
 namespace internal {
 
-TaskTracker::TaskTracker() {}
+TaskTracker::TaskTracker() : task_runs_(0), task_runs_cv_(&lock_) {}
 
 TaskTracker::~TaskTracker() {}
 
@@ -17,18 +17,26 @@
 }
 
 void TaskTracker::RunTask(const Closure& task, int i) {
-  AutoLock lock(task_run_counts_lock_);
+  AutoLock lock(lock_);
   if (!task.is_null()) {
     task.Run();
   }
   ++task_run_counts_[i];

[jar (doing other things), 2013/02/22 23:39:47]

aklin: Why do we increment count, when we *don't* run??

[michaeln, 2013/02/23 02:38:46]

In an effort to speed the process... i'll take a stab at an answer.

  Closure empty;
  empty.Run(); // This will crash

For the sake of convenience some of the test fixtures post wrapped empty/null
closures. For example, in TYPED_TEST_P(TaskRunnerTest, Basic), a bunch of empty
wrapped tasks are posted.

  const Closure& ith_task = this->task_tracker_->WrapTask(Closure(), i);

What's being counted is how many tasks the SequencnedWorkerPool processes, SWP
is calling TaskTracker::RunTask, internally that method may or may not call the
wrapped 'task' depending on how it was composed.

[akalin, 2013/02/26 00:12:23]

Yes, this is correct.  Perhaps add a comment explaining this?

+  ++task_runs_;
+  task_runs_cv_.Signal();
 }
 
 std::map<int, int> TaskTracker::GetTaskRunCounts() const {
-  AutoLock lock(task_run_counts_lock_);
+  AutoLock lock(lock_);
   return task_run_counts_;
 }
 
+void TaskTracker::WaitForTasksToComplete(int count) {

[jar (doing other things), 2013/02/22 23:39:47]

nit: rename, and use >=

+  AutoLock lock(lock_);
+  while (task_runs_ != count)
+    task_runs_cv_.Wait();
+}
+
 void ExpectRunsTasksOnCurrentThread(
     bool expected_value,
     const scoped_refptr<TaskRunner>& task_runner) {