Add handle waiting to StashBackend.

extensions/browser/mojo/stash_backend.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 EXTENSIONS_BROWSER_MOJO_STASH_BACKEND_H_
 #define EXTENSIONS_BROWSER_MOJO_STASH_BACKEND_H_
 
 #include <vector>
 
+#include "base/callback.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "extensions/common/mojo/stash.mojom.h"
 #include "third_party/mojo/src/mojo/public/cpp/bindings/interface_request.h"
 
 namespace extensions {
 
 // A backend that provides access to StashService for a single extension.
 class StashBackend {
  public:
-  StashBackend();
+  explicit StashBackend(const base::Closure& on_handle_readable);
   ~StashBackend();
 
   // Creates a StashService that forwards calls to this StashBackend and bind it
   // to |request|.
   void BindToRequest(mojo::InterfaceRequest<StashService> request);
 
   // Adds the StashedObjects contained within |stash| to the stash.
   void AddToStash(mojo::Array<StashedObjectPtr> stash);
 
   // Returns all StashedObjects added to the stash since the last call to
   // RetrieveStash.
   mojo::Array<StashedObjectPtr> RetrieveStash();
 
  private:
+  class StashEntry;
+
+  // Invoked when a handle is readable.
+  void OnHandleReady();
+
   // The objects that have been stashed.
-  mojo::Array<StashedObjectPtr> stashed_objects_;
+  std::vector<linked_ptr<StashEntry>> stashed_objects_;
+
+  // The callback to call when a handle is readable.
+  const base::Closure on_handle_readable_;
+
+  // Whether a handle has become readable since the last RetrieveStash() call.
+  bool has_notified_;
 
   base::WeakPtrFactory<StashBackend> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(StashBackend);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_MOJO_STASH_BACKEND_H_