EDK: Add PlatformHandleWatcher to Channel (and ChannelManager) classes.

mojo/edk/system/message_pipe_test_utils.cc

Index: mojo/edk/system/message_pipe_test_utils.cc
diff --git a/mojo/edk/system/message_pipe_test_utils.cc b/mojo/edk/system/message_pipe_test_utils.cc
index 208ffcea9c55b64e274250988beb0331cf3067fc..c36dd6e84ecba6d453e120f16c793fb9119f7aad 100644
--- a/mojo/edk/system/message_pipe_test_utils.cc
+++ b/mojo/edk/system/message_pipe_test_utils.cc
@@ -84,7 +84,9 @@ void ChannelThread::InitChannelOnIOThread(
 
   // Create and initialize |Channel|.
   channel_ = MakeRefCounted<Channel>(platform_support_);
-  channel_->Init(RawChannel::Create(platform_handle.Pass()));
+  channel_->Init(test_io_thread_.task_runner().Clone(),
+                 test_io_thread_.platform_handle_watcher(),
+                 RawChannel::Create(platform_handle.Pass()));
 
   // Start the bootstrap endpoint.
   // Note: On the "server" (parent process) side, we need not attach/run the