Mojo: Cancel WaitingCallbacks when their HandleWrappers are closed.

mojo/bindings/js/handle.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #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"
 #include "mojo/public/cpp/system/core.h"
 
 namespace gin {
 
 // Wrapper for mojo Handles exposed to JavaScript. This ensures the Handle
 // 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,
                                            MojoHandle handle) {
     return gin::CreateHandle(isolate, new HandleWrapper(handle));
   }
 
   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
 // MojoHandle, since that will do a simple int32 conversion. It's unfortunate
 // there's no way to prevent against accidental use.
 // TODO(mpcomplete): define converters for all Handle subtypes.
 template<>
 struct Converter<mojo::Handle> {
   static v8::Handle<v8::Value> ToV8(v8::Isolate* isolate,
                                     const mojo::Handle& val);
@@ skipping 22 matching lines @@
       return false;
     }
     *out = gin::Handle<gin::HandleWrapper>(val, object);
     return true;
   }
 };
 
 }  // namespace gin
 
 #endif  // MOJO_BINDINGS_JS_HANDLE_H_