Mojo Example that demos the difference between providing and requesting an interface

mojo/public/cpp/utility/lib/run_loop.cc

 // 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.
 
 #include "mojo/public/cpp/utility/run_loop.h"
 
 #include <assert.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 201 matching lines @@
     if (result == MOJO_RESULT_INVALID_ARGUMENT ||
         result == MOJO_RESULT_FAILED_PRECONDITION) {
       // Remove the handle first, this way if OnHandleError() tries to remove
       // the handle our iterator isn't invalidated.
       assert(handler_data_.find(wait_state.handles[i]) != handler_data_.end());
       RunLoopHandler* handler = handler_data_[wait_state.handles[i]].handler;
       handler_data_.erase(wait_state.handles[i]);
       handler->OnHandleError(wait_state.handles[i], result);
       return true;
     }
-    assert(MOJO_RESULT_DEADLINE_EXCEEDED == result);
+    assert(MOJO_RESULT_DEADLINE_EXCEEDED == result || MOJO_RESULT_OK == result);
   }
   return false;
 }
 
 RunLoop::WaitState RunLoop::GetWaitState(bool non_blocking) const {
   WaitState wait_state;
   MojoTimeTicks min_time = kInvalidTimeTicks;
   for (HandleToHandlerData::const_iterator i = handler_data_.begin();
        i != handler_data_.end();
        ++i) {
@@ skipping 37 matching lines @@
     // std::priority_queue<> puts the least element at the end of the queue. We
     // want the soonest eligible task to be at the head of the queue, so
     // run_times further in the future are considered lesser.
     return run_time > other.run_time;
   }
 
   return sequence_number > other.sequence_number;
 }
 
 }  // namespace mojo