EDK: Add TaskRunner and PlatformHandleWatcher to RawChannel.

mojo/edk/system/channel.cc

Index: mojo/edk/system/channel.cc
diff --git a/mojo/edk/system/channel.cc b/mojo/edk/system/channel.cc
index 74462243c1cdf072a226173f1288bbea7c9c83cb..b52cba61157a5658a59b6cae5495913a75e488ad 100644
--- a/mojo/edk/system/channel.cc
+++ b/mojo/edk/system/channel.cc
@@ -47,9 +47,7 @@ void Channel::Init(RefPtr<TaskRunner>&& io_task_runner,
   // becomes thread-safe.
   DCHECK(!is_running_);
   raw_channel_ = std::move(raw_channel);
-  // TODO(vtl): Add explicit |io_task_runner| and |io_watcher| arguments to
-  // |RawChannel::Init()| and pass them on.
-  raw_channel_->Init(this);
+  raw_channel_->Init(std::move(io_task_runner), io_watcher, this);
   is_running_ = true;
 }