[net/dns] Perform A/AAAA queries for AF_UNSPEC resolutions in parallel.

net/base/prioritized_dispatcher_unittest.cc

Index: net/base/prioritized_dispatcher_unittest.cc
===================================================================
--- net/base/prioritized_dispatcher_unittest.cc	(revision 212872)
+++ net/base/prioritized_dispatcher_unittest.cc	(working copy)
@@ -52,13 +52,17 @@
       return handle_;
     }
 
-    void Add() {
+    void Add(bool at_head) {
       CHECK(handle_.is_null());
       CHECK(!running_);
       size_t num_queued = dispatcher_->num_queued_jobs();
       size_t num_running = dispatcher_->num_running_jobs();
 
-      handle_ = dispatcher_->Add(this, priority_);
+      if (!at_head) {
+        handle_ = dispatcher_->Add(this, priority_);
+      } else {
+        handle_ = dispatcher_->AddAtHead(this, priority_);
+      }
 
       if (handle_.is_null()) {
         EXPECT_EQ(num_queued, dispatcher_->num_queued_jobs());
@@ -140,10 +144,17 @@
   TestJob* AddJob(char data, Priority priority) {
     TestJob* job = new TestJob(dispatcher_.get(), data, priority, &log_);
     jobs_.push_back(job);
-    job->Add();
+    job->Add(false);
     return job;
   }
 
+  TestJob* AddJobAtHead(char data, Priority priority) {
+    TestJob* job = new TestJob(dispatcher_.get(), data, priority, &log_);
+    jobs_.push_back(job);
+    job->Add(true);
+    return job;
+  }
+
   void Expect(std::string log) {
     EXPECT_EQ(0u, dispatcher_->num_queued_jobs());
     EXPECT_EQ(0u, dispatcher_->num_running_jobs());
@@ -202,6 +213,33 @@
   Expect("a.c.d.b.e.");
 }
 
+TEST_F(PrioritizedDispatcherTest, AddAtHead) {
+  PrioritizedDispatcher::Limits limits(NUM_PRIORITIES, 1);
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', MEDIUM);
+  TestJob* job_b = AddJobAtHead('b', MEDIUM);
+  TestJob* job_c = AddJobAtHead('c', HIGHEST);
+  TestJob* job_d = AddJobAtHead('d', HIGHEST);
+  TestJob* job_e = AddJobAtHead('e', MEDIUM);
+  TestJob* job_f = AddJob('f', MEDIUM);
+
+  ASSERT_TRUE(job_a->running());
+  job_a->Finish();
+  ASSERT_TRUE(job_d->running());
+  job_d->Finish();
+  ASSERT_TRUE(job_c->running());
+  job_c->Finish();
+  ASSERT_TRUE(job_e->running());
+  job_e->Finish();
+  ASSERT_TRUE(job_b->running());
+  job_b->Finish();
+  ASSERT_TRUE(job_f->running());
+  job_f->Finish();
+
+  Expect("a.d.c.e.b.f.");
+}
+
 TEST_F(PrioritizedDispatcherTest, EnforceLimits) {
   // Reserve 2 for HIGHEST and 1 for LOW or higher.
   // This leaves 2 for LOWEST or lower.