Mojo C++ bindings: remove unnecessary getters/params of AssociatedGroup.

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

Index: mojo/public/cpp/bindings/lib/binding_state.h
diff --git a/mojo/public/cpp/bindings/lib/binding_state.h b/mojo/public/cpp/bindings/lib/binding_state.h
index 209b3adf5df496a119f48c8de5517a89679f5f27..0b0dbee0026d07be01c722702eb8da9eacf1ea44 100644
--- a/mojo/public/cpp/bindings/lib/binding_state.h
+++ b/mojo/public/cpp/bindings/lib/binding_state.h
@@ -16,7 +16,6 @@
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
-#include "mojo/public/cpp/bindings/associated_group.h"
 #include "mojo/public/cpp/bindings/bindings_export.h"
 #include "mojo/public/cpp/bindings/connection_error_callback.h"
 #include "mojo/public/cpp/bindings/filter_chain.h"
@@ -69,10 +68,6 @@ class MOJO_CPP_BINDINGS_EXPORT BindingStateBase {
     return router_->handle();
   }
 
-  AssociatedGroup* associated_group() {
-    return endpoint_client_ ? endpoint_client_->associated_group() : nullptr;
-  }
-
   void FlushForTesting();
 
   void EnableTestingMode();