Adds lots of Mojo documentation

mojo/edk/system/dispatcher.h

 // Copyright 2013 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.
 
 #ifndef MOJO_EDK_SYSTEM_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_DISPATCHER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 36 matching lines @@
     scoped_refptr<Dispatcher> dispatcher;
     MojoHandle local_handle;
   };
 
   enum class Type {
     UNKNOWN = 0,
     MESSAGE_PIPE,
     DATA_PIPE_PRODUCER,
     DATA_PIPE_CONSUMER,
     SHARED_BUFFER,
-    WAIT_SET,
     WATCHER,
 
     // "Private" types (not exposed via the public interface):
     PLATFORM_HANDLE = -1,
   };
 
   // All Dispatchers must minimally implement these methods.
 
   virtual Type GetType() const = 0;
   virtual MojoResult Close() = 0;
@@ skipping 169 matching lines @@
 // So logging macros and |DCHECK_EQ()|, etc. work.
 MOJO_SYSTEM_IMPL_EXPORT inline std::ostream& operator<<(std::ostream& out,
                                                         Dispatcher::Type type) {
   return out << static_cast<int>(type);
 }
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_DISPATCHER_H_