Allow platform apps to respond to Web Intents

chrome/browser/extensions/web_intent_callbacks.h

+// Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_WEB_INTENT_CALLBACKS_H_
+#define CHROME_BROWSER_EXTENSIONS_WEB_INTENT_CALLBACKS_H_
+
+#include <set>
+
+#include "base/compiler_specific.h"
+#include "base/memory/singleton.h"
+#include "base/observer_list.h"
+#include "chrome/browser/profiles/profile_keyed_service.h"
+#include "chrome/browser/profiles/profile_keyed_service_factory.h"
+#include "ui/gfx/native_widget_types.h"

[benwells, 2012/08/13 08:27:29]

Are all these includes needed?

[thorogood, 2012/08/14 02:59:08]

Done.

+#include "webkit/glue/web_intent_reply_data.h"
+
+class Profile;
+
+namespace content {
+class WebContents;
+class WebIntentsDispatcher;
+}
+
+namespace extensions {
+class Extension;
+
+// The WebIntentCallbacks class tracks the pending callbacks for web intents
+// that have been delivered to platform apps, for a particular profile.
+class WebIntentCallbacks : public ProfileKeyedService {

[benwells, 2012/08/13 08:27:29]

I know we're now in the extensions namespace, but it might be good to make it
clear this is just for new-style-packaged apps, not extensions in general.

[thorogood, 2012/08/14 02:59:08]

Done.

[benwells, 2012/08/14 06:57:07]

Ah .. I meant by changing the class name, but I'm not too fussed.

[thorogood, 2012/08/15 06:15:49]

Ok. What about PlatformAppIntentRegistry?

+ public:
+  WebIntentCallbacks();
+  virtual ~WebIntentCallbacks();
+
+  // Returns the instance for the given profile. This is a convenience wrapper
+  // around WebIntentCallbacks::Factory::GetForProfile.
+  static WebIntentCallbacks* Get(Profile* profile);
+
+  // Registers the callback for the Web Intent we're about to dispatch to the
+  // given extension. Returns an identifier that should later be dispatched to
+  // RetrieveCallback in order to invoke the callback registered here.
+  int RegisterCallback(const Extension* extension,
+                       content::WebIntentsDispatcher* dispatcher,
+                       content::WebContents* source);
+
+  // Retrieves the callback for the given identifier, for a response from the
+  // specified extension. This will clear the callback. If there is no callback
+  // registered under this identifier, then this will return NULL.
+  content::WebIntentsDispatcher* RetrieveCallback(const Extension* extension,
+                                                  int intent_id);
+
+ private:
+  typedef std::map<std::string, content::WebIntentsDispatcher*> CallbackMap;

[benwells, 2012/08/13 08:27:29]

Is there any chance of us holding onto the dispatcher after it's deleted? Can we
hold a reference or something so we're not relying on assumptions about how
other code (which might change) works?

[thorogood, 2012/08/14 02:59:08]

So: I've done a bit of checking. What I've implicitly done here is, on
RegisterCallback, ownership of the WebIntentsDispatcher is actually by this
class. I've documented this explicitly, and ensured that in our cleanup  case,
we delete the dispatcher.

On RetrieveCallback, we transfer ownership to the caller, who then invokes
SendReplyMessage, which causes the object to be deleted. I've also documented
the RetrieveCallback method.

+
+  class Factory : public ProfileKeyedServiceFactory {
+   public:
+    static WebIntentCallbacks* GetForProfile(Profile* profile);
+
+    static Factory* GetInstance();
+   private:
+    friend struct DefaultSingletonTraits<Factory>;
+
+    Factory();
+    virtual ~Factory();
+
+    // ProfileKeyedServiceFactory
+    virtual ProfileKeyedService* BuildServiceInstanceFor(
+        Profile* profile) const OVERRIDE;
+  };
+
+  class SourceObserver;
+
+  // Used as an incrementing ID for callback keys.
+  int last_id_;
+
+  // Stores all pending callbacks sent to platform apps.
+  CallbackMap pending_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_WEB_INTENT_CALLBACKS_H_