Rename //toolchain/common to base (#3101)

Renaming per #3100

toolchain/base/pretty_stack_trace_function.h

@@ -0,0 +1,28 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef CARBON_TOOLCHAIN_BASE_PRETTY_STACK_TRACE_FUNCTION_H_
+#define CARBON_TOOLCHAIN_BASE_PRETTY_STACK_TRACE_FUNCTION_H_
+
+#include <functional>
+
+#include "llvm/Support/PrettyStackTrace.h"
+
+namespace Carbon {
+
+class PrettyStackTraceFunction : public llvm::PrettyStackTraceEntry {
+ public:
+  explicit PrettyStackTraceFunction(std::function<void(llvm::raw_ostream&)> fn)
+      : fn_(std::move(fn)) {}
+  ~PrettyStackTraceFunction() override = default;
+
+  auto print(llvm::raw_ostream& output) const -> void override { fn_(output); }
+
+ private:
+  const std::function<void(llvm::raw_ostream&)> fn_;
+};
+
+}  // namespace Carbon
+
+#endif  // CARBON_TOOLCHAIN_BASE_PRETTY_STACK_TRACE_FUNCTION_H_