Mojo: Make Channel take a RawChannel rather than creating it.

mojo/system/channel.h

Index: mojo/system/channel.h
diff --git a/mojo/system/channel.h b/mojo/system/channel.h
index 4af6daa8a0acca9a613558d9c17b3a397e766db5..fe876beaf364d5a3e2e27f7840ef4495aa9e4da6 100644
--- a/mojo/system/channel.h
+++ b/mojo/system/channel.h
@@ -59,11 +59,9 @@ class MOJO_SYSTEM_IMPL_EXPORT Channel
 
   // This must be called on the creation thread before any other methods are
   // called, and before references to this object are given to any other
-  // threads. |handle| should be a handle to a (platform-appropriate)
-  // bidirectional communication channel (e.g., a socket on POSIX, a named pipe
-  // on Windows). Returns true on success. On failure, no other methods should
-  // be called (including |Shutdown()|).
-  bool Init(embedder::ScopedPlatformHandle handle);
+  // threads. |raw_channel| should be uninitialized. Returns true on success. On
+  // failure, no other methods should be called (including |Shutdown()|).
+  bool Init(scoped_ptr<RawChannel> raw_channel);
 
   // This must be called on the creation thread before destruction (which can
   // happen on any thread).