Add FlushForTesting to InterfacePtr and Binding.

mojo/public/cpp/bindings/interface_endpoint_client.h

Index: mojo/public/cpp/bindings/interface_endpoint_client.h
diff --git a/mojo/public/cpp/bindings/interface_endpoint_client.h b/mojo/public/cpp/bindings/interface_endpoint_client.h
index af9347ccc2397b40dab84598be0eb548795bb670..e16bcd0a4884d420bb2782698bfe2d4bd87c6a59 100644
--- a/mojo/public/cpp/bindings/interface_endpoint_client.h
+++ b/mojo/public/cpp/bindings/interface_endpoint_client.h
@@ -18,6 +18,8 @@
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/public/cpp/bindings/filter_chain.h"
+#include "mojo/public/cpp/bindings/lib/control_message_handler.h"
+#include "mojo/public/cpp/bindings/lib/control_message_proxy.h"
 #include "mojo/public/cpp/bindings/message.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
 
@@ -38,7 +40,8 @@ class InterfaceEndpointClient : public MessageReceiverWithResponder {
                           MessageReceiverWithResponderStatus* receiver,
                           std::unique_ptr<MessageReceiver> payload_validator,
                           bool expect_sync_requests,
-                          scoped_refptr<base::SingleThreadTaskRunner> runner);
+                          scoped_refptr<base::SingleThreadTaskRunner> runner,
+                          uint32_t interface_version);
   ~InterfaceEndpointClient() override;
 
   // Sets the error handler to receive notifications when an error is
@@ -89,6 +92,10 @@ class InterfaceEndpointClient : public MessageReceiverWithResponder {
   bool HandleIncomingMessage(Message* message);
   void NotifyError();
 
+  internal::ControlMessageProxy* control_message_proxy() {
+    return &control_message_proxy_;
+  }
+
  private:
   // Maps from the id of a response to the MessageReceiver that handles the
   // response.
@@ -147,6 +154,9 @@ class InterfaceEndpointClient : public MessageReceiverWithResponder {
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
+  internal::ControlMessageProxy control_message_proxy_;
+  internal::ControlMessageHandler control_message_handler_;
+
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<InterfaceEndpointClient> weak_ptr_factory_;