Add FlushForTesting to InterfacePtr and Binding.

mojo/public/cpp/bindings/interface_ptr.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_BINDINGS_INTERFACE_PTR_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_PTR_H_
 
 #include <stdint.h>
 #include <utility>
 
@@ skipping 96 matching lines @@
   // end of the message pipe asynchronously. This does nothing if it's already
   // known that the remote side supports the specified version, i.e., if
   // |version <= this->version()|.
   //
   // After calling RequireVersion() with a version not supported by the remote
   // side, all subsequent calls to interface methods will be ignored.
   void RequireVersion(uint32_t version) {
     internal_state_.RequireVersion(version);
   }
 
+  // Sends a no-op message on the underlying message pipe and runs the current
+  // message loop until its response is received. This can be used in tests to
+  // verify that no message was sent on a message pipe in response to some
+  // stimulus.
+  void FlushForTesting() { internal_state_.FlushForTesting(); }
+
   // Closes the bound message pipe (if any) and returns the pointer to the
   // unbound state.
   void reset() {
     State doomed;
     internal_state_.Swap(&doomed);
   }
 
   // Whether there are any associated interfaces running on the pipe currently.
   bool HasAssociatedInterfaces() const {
     return internal_state_.HasAssociatedInterfaces();
@@ skipping 96 matching lines @@
         base::ThreadTaskRunnerHandle::Get()) {
   InterfacePtr<Interface> ptr;
   if (info.is_valid())
     ptr.Bind(std::move(info), std::move(runner));
   return std::move(ptr);
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_PTR_H_