Implement throttling logic for fetching affiliation information.

base/test/test_mock_time_task_runner.cc

Index: base/test/test_mock_time_task_runner.cc
diff --git a/base/test/test_mock_time_task_runner.cc b/base/test/test_mock_time_task_runner.cc
index 169839124d9e29f7ea60ab4f356020ebcb5fb0f0..442d99190b0b87060337b6b67d9d60f7f1d47051 100644
--- a/base/test/test_mock_time_task_runner.cc
+++ b/base/test/test_mock_time_task_runner.cc
@@ -102,6 +102,11 @@ bool TestMockTimeTaskRunner::HasPendingTask() const {
   return !tasks_.empty();
 }
 
+size_t TestMockTimeTaskRunner::GetPendingTaskCount() const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return tasks_.size();
+}
+
 TimeDelta TestMockTimeTaskRunner::NextPendingTaskDelay() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return tasks_.empty() ? TimeDelta::Max() : tasks_.top().GetTimeToRun() - now_;