Remove ChannelInterface and replace it with Channel
diff --git a/test/cpp/qps/client.h b/test/cpp/qps/client.h
index 1c4f463..5395d02 100644
--- a/test/cpp/qps/client.h
+++ b/test/cpp/qps/client.h
@@ -125,11 +125,11 @@
       channel_ = CreateTestChannel(target, config.enable_ssl());
       stub_ = TestService::NewStub(channel_);
     }
-    ChannelInterface* get_channel() { return channel_.get(); }
+    Channel* get_channel() { return channel_.get(); }
     TestService::Stub* get_stub() { return stub_.get(); }
 
    private:
-    std::shared_ptr<ChannelInterface> channel_;
+    std::shared_ptr<Channel> channel_;
     std::unique_ptr<TestService::Stub> stub_;
   };
   std::vector<ClientChannelInfo> channels_;