Add FlushForTesting to InterfacePtr and Binding.

mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h

Index: mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h
diff --git a/mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h b/mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h
index c7f74fbb9c370cc76ba0cc3ffe5d0688d9f8c35d..30a3c428e92ccbe21bdadbce7a6480417fa9546b 100644
--- a/mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h
+++ b/mojo/public/cpp/bindings/lib/associated_interface_ptr_state.h
@@ -22,6 +22,7 @@
 #include "mojo/public/cpp/bindings/associated_interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/interface_endpoint_client.h"
 #include "mojo/public/cpp/bindings/interface_id.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/scoped_interface_endpoint_handle.h"
 #include "mojo/public/cpp/system/message_pipe.h"
@@ -52,12 +53,11 @@ class AssociatedInterfacePtrState {
   }
 
   void QueryVersion(const base::Callback<void(uint32_t)>& callback) {
-    // Do a static cast in case the interface contains methods with the same
-    // name. It is safe to capture |this| because the callback won't be run
-    // after this object goes away.
-    static_cast<ControlMessageProxy*>(proxy_.get())
-        ->QueryVersion(base::Bind(&AssociatedInterfacePtrState::OnQueryVersion,
-                                  base::Unretained(this), callback));
+    // It is safe to capture |this| because the callback won't be run after this
+    // object goes away.
+    endpoint_client_->control_message_proxy()->QueryVersion(
+        base::Bind(&AssociatedInterfacePtrState::OnQueryVersion,
+                   base::Unretained(this), callback));
   }
 
   void RequireVersion(uint32_t version) {
@@ -65,9 +65,11 @@ class AssociatedInterfacePtrState {
       return;
 
     version_ = version;
-    // Do a static cast in case the interface contains methods with the same
-    // name.
-    static_cast<ControlMessageProxy*>(proxy_.get())->RequireVersion(version);
+    endpoint_client_->control_message_proxy()->RequireVersion(version);
+  }
+
+  void FlushForTesting() {
+    endpoint_client_->control_message_proxy()->FlushForTesting();
   }
 
   void Swap(AssociatedInterfacePtrState* other) {
@@ -85,10 +87,12 @@ class AssociatedInterfacePtrState {
     DCHECK(info.is_valid());
 
     version_ = info.version();
+    // The version is only queried from the client so the value passed here
+    // will not be used.
     endpoint_client_.reset(new InterfaceEndpointClient(
         info.PassHandle(), nullptr,
         base::WrapUnique(new typename Interface::ResponseValidator_()), false,
-        std::move(runner)));
+        std::move(runner), 0u));
     proxy_.reset(new Proxy(endpoint_client_.get()));
     proxy_->serialization_context()->group_controller =
         endpoint_client_->group_controller();