Implement MessagePumpMojo using WaitSet.

mojo/public/cpp/system/handle.h

 // Copyright 2014 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_PUBLIC_CPP_SYSTEM_HANDLE_H_
 #define MOJO_PUBLIC_CPP_SYSTEM_HANDLE_H_
 
 #include <assert.h>
 #include <limits>
 
@@ skipping 267 matching lines @@
 // Most users should typically use |Close()| (above) instead.
 inline MojoResult CloseRaw(Handle handle) {
   return MojoClose(handle.value());
 }
 
 // Strict weak ordering, so that |Handle|s can be used as keys in |std::map|s,
 inline bool operator<(const Handle a, const Handle b) {
   return a.value() < b.value();
 }
 
+// Comparison, so that |Handle|s can be used as keys in hash maps.
+inline bool operator==(const Handle a, const Handle b) {
+  return a.value() == b.value();
+}
+
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_SYSTEM_HANDLE_H_