Deprecate grpc::thread and sync in favor of std::thread,mutex,etc
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 559b5bf8..a66ec4a 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -33,9 +33,10 @@
 
 #include <grpc++/server_context.h>
 
+#include <mutex>
+
 #include <grpc++/completion_queue.h>
 #include <grpc++/impl/call.h>
-#include <grpc++/impl/sync.h>
 #include <grpc++/support/time.h>
 #include <grpc/compression.h>
 #include <grpc/grpc.h>
@@ -76,20 +77,20 @@
 
  private:
   bool CheckCancelledNoPluck() {
-    grpc::lock_guard<grpc::mutex> g(mu_);
+    std::lock_guard<std::mutex> g(mu_);
     return finalized_ ? (cancelled_ != 0) : false;
   }
 
   bool has_tag_;
   void* tag_;
-  grpc::mutex mu_;
+  std::mutex mu_;
   int refs_;
   bool finalized_;
   int cancelled_;
 };
 
 void ServerContext::CompletionOp::Unref() {
-  grpc::unique_lock<grpc::mutex> lock(mu_);
+  std::unique_lock<std::mutex> lock(mu_);
   if (--refs_ == 0) {
     lock.unlock();
     delete this;
@@ -105,7 +106,7 @@
 }
 
 bool ServerContext::CompletionOp::FinalizeResult(void** tag, bool* status) {
-  grpc::unique_lock<grpc::mutex> lock(mu_);
+  std::unique_lock<std::mutex> lock(mu_);
   finalized_ = true;
   bool ret = false;
   if (has_tag_) {