EDK: Remove mojo::platform::MessageLoopForIO and add PlatformHandleWatcher.

mojo/edk/platform/test_message_loops.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file declares factory functions (which must be implemented by the
 // embedder) for message loops to be used in tests.
 
 #ifndef MOJO_EDK_PLATFORM_TEST_MESSAGE_LOOPS_H_
 #define MOJO_EDK_PLATFORM_TEST_MESSAGE_LOOPS_H_
 
 #include <memory>
 
 namespace mojo {
 namespace platform {
 
 class MessageLoop;
-class MessageLoopForIO;
+class PlatformHandleWatcher;
 
 namespace test {
 
-// Creates a basic |platform::MessageLoop|, to be used by tests. This must be
-// implemented by the embedder (if building tests that require it).
+// Creates a basic |MessageLoop|, to be used by tests. This must be implemented
+// by the embedder (if building tests that require it).
 std::unique_ptr<MessageLoop> CreateTestMessageLoop();
 
-// Creates a basic |platform::MessageLoopForIO|, to be used by tests. This must
-// be implemented by the embedder (if building tests that require it).
-std::unique_ptr<MessageLoopForIO> CreateTestMessageLoopForIO();
+// Creates a basic |MessageLoop| that supports watching |PlatformHandle|s, to be
+// used by tests. This must be implemented by the embedder (if building tests
+// that require it). The "out" |PlatformHandleWatcher| is valid while the
+// returned |MessageLoop| is alive (and will watch handles while it is running).
+std::unique_ptr<MessageLoop> CreateTestMessageLoopForIO(
+    PlatformHandleWatcher** platform_handle_watcher);
 
 }  // namespace test
 }  // namespace platform
 }  // namespace mojo
 
 #endif  // MOJO_EDK_PLATFORM_TEST_MESSAGE_LOOPS_H_