[Approach 3] Pre-allocate IncomigTaskQueue before MessageLoop for faster thread startup

base/threading/thread_unittest.cc

Index: base/threading/thread_unittest.cc
diff --git a/base/threading/thread_unittest.cc b/base/threading/thread_unittest.cc
index f4d024f1a26a79fb53ac599ff5ba3c8202727da8..3f6a10b9c6b725c2bdd31cf3425b1d519259891c 100644
--- a/base/threading/thread_unittest.cc
+++ b/base/threading/thread_unittest.cc
@@ -195,11 +195,12 @@ TEST_F(ThreadTest, ThreadName) {
   EXPECT_EQ("ThreadName", a.thread_name());
 }
 
-// Make sure we can't use a thread between Start() and Init().
+// Make sure Init() is called after Start() and before
+// WaitUntilThreadInitialized() returns.
 TEST_F(ThreadTest, SleepInsideInit) {
   SleepInsideInitThread t;
   EXPECT_FALSE(t.InitCalled());
-  t.Start();
+  t.StartAndWait();
   EXPECT_TRUE(t.InitCalled());
 }