Provide an iOS message pump for IO implementation.

base/message_loop.h

Index: base/message_loop.h
diff --git a/base/message_loop.h b/base/message_loop.h
index 74dfe659cc92292326a7c2e411ab19076b4ea763..405d98be9ecb083e874585b5de4d3da886a8fb03 100644
--- a/base/message_loop.h
+++ b/base/message_loop.h
@@ -26,6 +26,8 @@
 // We need this to declare base::MessagePumpWin::Dispatcher, which we should
 // really just eliminate.
 #include "base/message_pump_win.h"
+#elif defined(OS_IOS)
+#include "base/message_pump_io_ios.h"
 #elif defined(OS_POSIX)
 #include "base/message_pump_libevent.h"
 #if !defined(OS_MACOSX) && !defined(OS_ANDROID)
@@ -388,7 +390,7 @@ class BASE_EXPORT MessageLoop : public base::MessagePump::Delegate {
   base::MessagePumpWin* pump_win() {
     return static_cast<base::MessagePumpWin*>(pump_.get());
   }
-#elif defined(OS_POSIX)
+#elif defined(OS_POSIX) && !defined(OS_IOS)
   base::MessagePumpLibevent* pump_libevent() {
     return static_cast<base::MessagePumpLibevent*>(pump_.get());
   }
@@ -613,6 +615,17 @@ class BASE_EXPORT MessageLoopForIO : public MessageLoop {
   typedef base::MessagePumpForIO::IOHandler IOHandler;
   typedef base::MessagePumpForIO::IOContext IOContext;
   typedef base::MessagePumpForIO::IOObserver IOObserver;
+#elif defined(OS_IOS)
+  typedef base::MessagePumpIOSForIO::Watcher Watcher;
+  typedef base::MessagePumpIOSForIO::FileDescriptorWatcher
+      FileDescriptorWatcher;
+  typedef base::MessagePumpIOSForIO::IOObserver IOObserver;
+
+  enum Mode {
+    WATCH_READ = base::MessagePumpIOSForIO::WATCH_READ,
+    WATCH_WRITE = base::MessagePumpIOSForIO::WATCH_WRITE,
+    WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE
+  };
 #elif defined(OS_POSIX)
   typedef base::MessagePumpLibevent::Watcher Watcher;
   typedef base::MessagePumpLibevent::FileDescriptorWatcher
@@ -657,6 +670,19 @@ class BASE_EXPORT MessageLoopForIO : public MessageLoop {
     return static_cast<base::MessagePumpForIO*>(pump_.get());
   }
 
+#elif defined(OS_IOS)
+  // Please see MessagePumpIOSForIO for definition.
+  bool WatchFileDescriptor(int fd,
+                           bool persistent,
+                           Mode mode,
+                           FileDescriptorWatcher *controller,
+                           Watcher *delegate);
+
+ private:
+  base::MessagePumpIOSForIO* pump_io() {
+    return static_cast<base::MessagePumpIOSForIO*>(pump_.get());
+  }
+
 #elif defined(OS_POSIX)
   // Please see MessagePumpLibevent for definition.
   bool WatchFileDescriptor(int fd,