Add a check to the registry before the intent infobar is shown.

chrome/browser/intents/register_intent_handler_infobar_delegate.h

 // Copyright (c) 2011 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_INTENTS_REGISTER_INTENT_HANDLER_INFOBAR_DELEGATE_H_
 #define CHROME_BROWSER_INTENTS_REGISTER_INTENT_HANDLER_INFOBAR_DELEGATE_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/string16.h"
 #include "chrome/browser/tab_contents/confirm_infobar_delegate.h"
 #include "webkit/glue/web_intent_service_data.h"
 
+class InfoBarTabHelper;
 class TabContents;
 class WebIntentsRegistry;
 
 // The InfoBar used to request permission for a site to be registered as an
 // Intent handler.
 class RegisterIntentHandlerInfoBarDelegate : public ConfirmInfoBarDelegate {
  public:
   RegisterIntentHandlerInfoBarDelegate(InfoBarTabHelper* infobar_helper,
                                        WebIntentsRegistry* registry,
                                        const WebIntentServiceData& service);
 
   // ConfirmInfoBarDelegate implementation.
   virtual Type GetInfoBarType() const OVERRIDE;
   virtual string16 GetMessageText() const OVERRIDE;
   virtual string16 GetButtonLabel(InfoBarButton button) const OVERRIDE;
   virtual bool Accept() OVERRIDE;
   virtual string16 GetLinkText() const OVERRIDE;
   virtual bool LinkClicked(WindowOpenDisposition disposition) OVERRIDE;
 
+  // This helper method checks the registry to see if the indicated service has
+  // already been registered. If all registration details are the same, it does

[James Hawkins, 2011/10/29 21:41:32]

This second sentence should probably be reworded to reflect what the method does
instead of what it does not do.  The whole thing could be simplified to:

"Shows the intent registration InfoBar iff |service| has not already been
registered."

[Greg Billock, 2011/10/31 17:07:09]

I like that.

+  // not show the infobar.
+  // |infobar_helper| is the infobar controller for the tab in which the infobar
+  // may be shown. Must not be null.
+  // |registry| is the data source for web intents. Must not be null.
+  // |service| is the candidate service to show the infobar for.
+  static void MaybeShowIntentInfoBar(InfoBarTabHelper* infobar_helper,
+                                     WebIntentsRegistry* registry,
+                                     const WebIntentServiceData& service);
+
  private:
   // The web intents registry to use. Weak pointer.
   WebIntentsRegistry* registry_;
 
   // The cached intent data bundle passed up from the renderer.
   WebIntentServiceData service_;
 
   DISALLOW_COPY_AND_ASSIGN(RegisterIntentHandlerInfoBarDelegate);
 };
 
 #endif  // CHROME_BROWSER_INTENTS_REGISTER_INTENT_HANDLER_INFOBAR_DELEGATE_H_