Update documentation for base::ResetAndReturn(Callback*)

docs/callback.md

Index: docs/callback.md
diff --git a/docs/callback.md b/docs/callback.md
index 6b7dd6931f5009a402696c7753c619a48ff98b62..37edad19ce0cd0ab25a9f6e28e7e14e69df5fc0a 100644
--- a/docs/callback.md
+++ b/docs/callback.md
@@ -152,6 +152,17 @@ void DoSomething(const RepeatingCallback<double(double)>& callback) {
 }
 ```
 
+If running a callback could result in its own destruction (e.g., if the callback
+recipient deletes the object the callback is a member of), the callback should
+be moved before it can be safely invoked. The `base::ResetAndReturn` method
+provides this functionality.
+
+```cpp
+Foo::RunCallback() {

[tzik, 2017/03/17 14:01:06]

nit: void Foo::RunCallback() {

[michaelpg, 2017/03/17 22:58:20]

whoops, done

+  base::ResetAndReturn(&foo_deleter_callback_).Run();
+}
+```
+
 ### Passing Unbound Input Parameters
 
 Unbound parameters are specified at the time a callback is `Run()`. They are