Exposed GetInProcessShmemArbiter() in ProducerEndpoint

This is needed to handle startup tracing (binding StartupTraceWriters)
in the in-process case.

Change-Id: Id1171a30a134ecd42dba661e5b5c2ab7cdae8300
diff --git a/src/tracing/core/tracing_service_impl.h b/src/tracing/core/tracing_service_impl.h
index bda8c29..474bd7b 100644
--- a/src/tracing/core/tracing_service_impl.h
+++ b/src/tracing/core/tracing_service_impl.h
@@ -88,6 +88,7 @@
     void CommitData(const CommitDataRequest&, CommitDataCallback) override;
     void SetSharedMemory(std::unique_ptr<SharedMemory>);
     std::unique_ptr<TraceWriter> CreateTraceWriter(BufferID) override;
+    SharedMemoryArbiter* GetInProcessShmemArbiter() override;
     void NotifyFlushComplete(FlushRequestID) override;
     void NotifyDataSourceStarted(DataSourceInstanceID) override;
     void NotifyDataSourceStopped(DataSourceInstanceID) override;
@@ -118,7 +119,6 @@
     friend class TracingServiceImplTest;
     ProducerEndpointImpl(const ProducerEndpointImpl&) = delete;
     ProducerEndpointImpl& operator=(const ProducerEndpointImpl&) = delete;
-    SharedMemoryArbiterImpl* GetShmemArbiter();
 
     ProducerID const id_;
     const uid_t uid_;