Provide an iOS message pump for IO implementation.

base/message_pump_libevent_unittest.cc

Index: base/message_pump_libevent_unittest.cc
diff --git a/base/message_pump_libevent_unittest.cc b/base/message_pump_libevent_unittest.cc
index 94245cec8a91eddbc43fddbd3ddbf8a8ea3a8d0b..e48a9c53090429921294408e2c4ea2efe7d15084 100644
--- a/base/message_pump_libevent_unittest.cc
+++ b/base/message_pump_libevent_unittest.cc
@@ -30,8 +30,8 @@ class MessagePumpLibeventTest : public testing::Test {
     Thread::Options options(MessageLoop::TYPE_IO, 0);
     ASSERT_TRUE(io_thread_.StartWithOptions(options));
     ASSERT_EQ(MessageLoop::TYPE_IO, io_thread_.message_loop()->type());
-    int err = pipe(pipefds_);
-    ASSERT_EQ(0, err);
+    int ret = pipe(pipefds_);
+    ASSERT_EQ(0, ret);
   }
 
   virtual void TearDown() OVERRIDE {
@@ -52,9 +52,11 @@ class MessagePumpLibeventTest : public testing::Test {
     pump->OnLibeventNotification(0, EV_WRITE | EV_READ, controller);
   }
 
+  int pipefds_[2];
+
+ private:
   MessageLoop ui_loop_;
   Thread io_thread_;
-  int pipefds_[2];
 };
 
 namespace {