Mojo: Cancel WaitingCallbacks when their HandleWrappers are closed.

mojo/bindings/js/handle.h

Index: mojo/bindings/js/handle.h
diff --git a/mojo/bindings/js/handle.h b/mojo/bindings/js/handle.h
index 35202b07ea674240bdc4b81c6702f718f8b9d696..8c94c95ac28c871de2de6ccf9a1f0e7c015d4908 100644
--- a/mojo/bindings/js/handle.h
+++ b/mojo/bindings/js/handle.h
@@ -5,6 +5,7 @@
 #ifndef MOJO_BINDINGS_JS_HANDLE_H_
 #define MOJO_BINDINGS_JS_HANDLE_H_
 
+#include "base/observer_list.h"
 #include "gin/converter.h"
 #include "gin/handle.h"
 #include "gin/wrappable.h"
@@ -16,6 +17,11 @@ namespace gin {
 // is Closed when its JS object is garbage collected.
 class HandleWrapper : public gin::Wrappable<HandleWrapper> {
  public:
+  class CloseObserver {

[sky, 2014/09/03 15:47:04]

Move this into its own file and make the destructor protected.

[Sam McNally, 2014/09/08 04:31:52]

Done.

+   public:
+    virtual ~CloseObserver() {}
+    virtual void OnHandleClosed() = 0;

[sky, 2014/09/03 15:47:04]

Isn't this sent before the close? Wouldn't OnWillCloseHandle be a better name?

[Sam McNally, 2014/09/08 04:31:52]

Done.

+  };
   static gin::WrapperInfo kWrapperInfo;
 
   static gin::Handle<HandleWrapper> Create(v8::Isolate* isolate,
@@ -25,12 +31,17 @@ class HandleWrapper : public gin::Wrappable<HandleWrapper> {
 
   mojo::Handle get() const { return handle_.get(); }
   mojo::Handle release() { return handle_.release(); }
-  void Close() { handle_.reset(); }
+  void Close();
+
+  void AddCloseObserver(CloseObserver* observer);
+  void RemoveCloseObserver(CloseObserver* observer);
 
  protected:
   HandleWrapper(MojoHandle handle);
   virtual ~HandleWrapper();
+  void NotifyCloseObservers();
   mojo::ScopedHandle handle_;

[sky, 2014/09/03 15:47:04]

nit: newline between 42/43.

[Sam McNally, 2014/09/08 04:31:52]

Done.

+  ObserverList<CloseObserver> close_observers_;
 };
 
 // Note: It's important to use this converter rather than the one for