[clangd] Replace UniqueFunction with llvm::unique_function.

One implementation of this ought to be enough for everyone.

llvm-svn: 336228
diff --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index 7e07c3f..a1298fd 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -566,7 +566,7 @@
 // within the callback.
 struct CompletionRecorder : public CodeCompleteConsumer {
   CompletionRecorder(const CodeCompleteOptions &Opts,
-                     UniqueFunction<void()> ResultsCallback)
+                     llvm::unique_function<void()> ResultsCallback)
       : CodeCompleteConsumer(Opts.getClangCompleteOpts(),
                              /*OutputIsBinary=*/false),
         CCContext(CodeCompletionContext::CCC_Other), Opts(Opts),
@@ -657,7 +657,7 @@
   CodeCompleteOptions Opts;
   std::shared_ptr<GlobalCodeCompletionAllocator> CCAllocator;
   CodeCompletionTUInfo CCTUInfo;
-  UniqueFunction<void()> ResultsCallback;
+  llvm::unique_function<void()> ResultsCallback;
 };
 
 class SignatureHelpCollector final : public CodeCompleteConsumer {