Mojo C++ bindings: error notification behavior related to sync calls.

mojo/public/cpp/bindings/lib/connector.cc

 // 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.
 
 #include "mojo/public/cpp/bindings/lib/connector.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 350 matching lines @@
   }
 
   if (should_stop_sync_handle_watch_)
     should_stop_sync_handle_watch_->data = true;
 }
 
 void Connector::HandleError(bool force_pipe_reset, bool force_async_handler) {
   if (error_ || !message_pipe_.is_valid())
     return;
 
+  if (during_sync_handle_watcher_callback() || paused_) {
+    // Enforce calling the error handler asynchronously if:
+    // - currently we are in a sync handle watcher callback. We don't want the
+    // error handler to reenter an ongoing sync call.
+    // - the user has paused receiving messages. We need to wait until the user
+    // starts receiving messages again.
+    force_async_handler = true;
+  }
+
   if (!force_pipe_reset && force_async_handler)
     force_pipe_reset = true;
 
-  if (paused_) {
-    // If the user has paused receiving messages, we shouldn't call the error
-    // handler right away. We need to wait until the user starts receiving
-    // messages again.
-    force_async_handler = true;
-  }
-
   if (force_pipe_reset) {
     CancelWait();
     MayAutoLock locker(lock_.get());
     Close(std::move(message_pipe_));
     MessagePipe dummy_pipe;
     message_pipe_ = std::move(dummy_pipe.handle0);
   } else {
     CancelWait();
   }
 
   if (force_async_handler) {
     if (!paused_)
       WaitToReadMore();
   } else {
     error_ = true;
     connection_error_handler_.Run();
   }
 }
 
 }  // namespace internal
 }  // namespace mojo