Introduce base::IgnoreReuse() to wrap OnceCallback into RepeatingCallback

base/callback_helpers.h

Index: base/callback_helpers.h
diff --git a/base/callback_helpers.h b/base/callback_helpers.h
index 6e0aee88822d85cee8d5481241ac26741629d9b3..8d622f86552a5ec622b65a88d14ecf02316a2a99 100644
--- a/base/callback_helpers.h
+++ b/base/callback_helpers.h
@@ -14,22 +14,64 @@
 #ifndef BASE_CALLBACK_HELPERS_H_
 #define BASE_CALLBACK_HELPERS_H_
 
+#include <utility>
+
+#include "base/atomicops.h"
+#include "base/bind.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "base/memory/ptr_util.h"
 
 namespace base {
 
 template <typename Signature,
           internal::CopyMode copy_mode,
           internal::RepeatMode repeat_mode>
-base::Callback<Signature, copy_mode, repeat_mode> ResetAndReturn(
-    base::Callback<Signature, copy_mode, repeat_mode>* cb) {
-  base::Callback<Signature, copy_mode, repeat_mode> ret(std::move(*cb));
+Callback<Signature, copy_mode, repeat_mode> ResetAndReturn(
+    Callback<Signature, copy_mode, repeat_mode>* cb) {
+  Callback<Signature, copy_mode, repeat_mode> ret(std::move(*cb));
   DCHECK(!*cb);
   return ret;
 }
 
+namespace internal {
+
+template <typename... Args>
+class AdaptCallbackForRepeatingHelper final {
+ public:
+  explicit AdaptCallbackForRepeatingHelper(OnceCallback<void(Args...)> callback)
+      : callback_(std::move(callback)) {
+    DCHECK(callback_);
+  }
+
+  void Run(Args... args) {
+    if (subtle::NoBarrier_AtomicExchange(&has_run_, 1))
+      return;
+    DCHECK(callback_);
+    std::move(callback_).Run(std::forward<Args>(args)...);
+  }
+
+ private:
+  volatile subtle::Atomic32 has_run_ = 0;
+  base::OnceCallback<void(Args...)> callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(AdaptCallbackForRepeatingHelper);
+};
+
+}  // namespace internal
+
+// Wraps the given OnceCallback into a RepeatingCallback that relays its
+// invocation to the original OnceCallback on the first invocation. The
+// following invocations are just ignored.
+template <typename... Args>
+RepeatingCallback<void(Args...)> AdaptCallbackForRepeating(
+    OnceCallback<void(Args...)> callback) {
+  using Helper = internal::AdaptCallbackForRepeatingHelper<Args...>;
+  return base::BindRepeating(&Helper::Run,
+                             base::MakeUnique<Helper>(std::move(callback)));
+}
+
 // ScopedClosureRunner is akin to std::unique_ptr<> for Closures. It ensures
 // that the Closure is executed no matter how the current scope exits.
 class BASE_EXPORT ScopedClosureRunner {