Don't block the tab when dispatching an intent until we're sure we're going to show a dialog.

chrome/browser/ui/intents/web_intent_picker_controller.cc

 // 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.
 
 #include "chrome/browser/ui/intents/web_intent_picker_controller.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 176 matching lines @@
 void WebIntentPickerController::SetIntentsDispatcher(
     content::WebIntentsDispatcher* intents_dispatcher) {
   intents_dispatcher_ = intents_dispatcher;
   intents_dispatcher_->RegisterReplyNotification(
       base::Bind(&WebIntentPickerController::OnSendReturnMessage,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 void WebIntentPickerController::ShowDialog(const string16& action,
                                            const string16& type) {
 
-  // As soon as the dialog is requested, block all input events
-  // on the original tab.
-  tab_contents_->constrained_window_tab_helper()->BlockTabContent(true);
-
   // Only show a picker once.
   // TODO(gbillock): There's a hole potentially admitting multiple
   // in-flight dispatches since we don't create the picker
   // in this method, but only after calling the registry.
   if (picker_shown_) {
     if (intents_dispatcher_) {
       intents_dispatcher_->SendReplyMessage(
           webkit_glue::WEB_INTENT_REPLY_FAILURE,
           ASCIIToUTF16("Simultaneous intent invocation."));
     }
@@ skipping 33 matching lines @@
       // required to find disposition set by service.)
       pending_async_count_++;
       GetWebIntentsRegistry(tab_contents_)->GetIntentServices(
           action, type, base::Bind(
               &WebIntentPickerController::WebIntentServicesForExplicitIntent,
               weak_ptr_factory_.GetWeakPtr()));
       return;
     }
   }
 
+  // As soon as the dialog is requested, block all input events
+  // on the original tab.
+  tab_contents_->constrained_window_tab_helper()->BlockTabContent(true);
   SetDialogState(kPickerSetup);
 
   pending_async_count_++;
   pending_registry_calls_count_++;
   GetWebIntentsRegistry(tab_contents_)->GetIntentServices(
       action, type,
           base::Bind(&WebIntentPickerController::OnWebIntentServicesAvailable,
               weak_ptr_factory_.GetWeakPtr()));
 
   GURL invoking_url = tab_contents_->web_contents()->GetURL();
@@ skipping 678 matching lines @@
   picker_->SetActionString(GetIntentActionString(
       UTF16ToUTF8(picker_model_->action())));
   picker_shown_ = true;
 }
 
 void WebIntentPickerController::ClosePicker() {
   SetDialogState(kPickerHidden);
   if (picker_)
     picker_->Close();
 }