Add IPC::ChannelProxy::Create() and IPC::SyncChannel::Create()

ipc/ipc_sync_channel.cc

Index: ipc/ipc_sync_channel.cc
diff --git a/ipc/ipc_sync_channel.cc b/ipc/ipc_sync_channel.cc
index 0e0018c7eae74745b91ade4655975278568d57bb..a7ed230e53cdeec5ab1e43f90701edb0c3662c78 100644
--- a/ipc/ipc_sync_channel.cc
+++ b/ipc/ipc_sync_channel.cc
@@ -404,19 +404,27 @@ base::WaitableEventWatcher::EventCallback
   return base::Bind(&SyncChannel::SyncContext::OnWaitableEventSignaled, this);
 }
 
-SyncChannel::SyncChannel(
+// static
+scoped_ptr<SyncChannel> SyncChannel::Create(
     const IPC::ChannelHandle& channel_handle,
     Channel::Mode mode,
     Listener* listener,
     base::SingleThreadTaskRunner* ipc_task_runner,
     bool create_pipe_now,
-    WaitableEvent* shutdown_event)
-    : ChannelProxy(new SyncContext(listener, ipc_task_runner, shutdown_event)) {
-  // The current (listener) thread must be distinct from the IPC thread, or else
-  // sending synchronous messages will deadlock.
-  DCHECK_NE(ipc_task_runner, base::ThreadTaskRunnerHandle::Get());
-  ChannelProxy::Init(channel_handle, mode, create_pipe_now);
-  StartWatching();
+    base::WaitableEvent* shutdown_event) {
+  scoped_ptr<SyncChannel> channel =
+      Create(listener, ipc_task_runner, shutdown_event);
+  channel->Init(channel_handle, mode, create_pipe_now);
+  return channel.Pass();
+}
+
+// static
+scoped_ptr<SyncChannel> SyncChannel::Create(
+    Listener* listener,
+    base::SingleThreadTaskRunner* ipc_task_runner,
+    WaitableEvent* shutdown_event) {
+  return make_scoped_ptr(
+      new SyncChannel(listener, ipc_task_runner, shutdown_event));
 }
 
 SyncChannel::SyncChannel(