removed unnecessary "virtual"

Removed unnecessary "virtual" keyword from CompletionQueue::Next.
Reverted two files that no longer need to be changed.

src/cpp/common/completion_queue_cc.cc

@@ -50,12 +50,6 @@ void CompletionQueue::CompleteAvalanching() {
   }
 }
 
-bool CompletionQueue::Next(void** tag, bool* ok) {
-  return (AsyncNextInternal(tag, ok,
-                            g_core_codegen_interface->gpr_inf_future(
-                                GPR_CLOCK_REALTIME)) != SHUTDOWN);
-}
-
 CompletionQueue::NextStatus CompletionQueue::AsyncNextInternal(
     void** tag, bool* ok, gpr_timespec deadline) {
   for (;;) {

test/cpp/codegen/codegen_test_minimal.cc

@@ -16,14 +16,9 @@
  *
  */
 
-#include <grpcpp/impl/codegen/completion_queue.h>
 #include <gtest/gtest.h>
 
 namespace grpc {
-
-// Unused implementation for the virtual "Next" method.
-bool CompletionQueue::Next(void** tag, bool* ok) { return false; }
-
 namespace {
 
 class CodegenTestMinimal : public ::testing::Test {};