Mojo: Fix DCHECK on middle-click in window manager.

mojo/examples/window_manager/window_manager.cc

 // 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.
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/strings/stringprintf.h"
 #include "mojo/examples/window_manager/window_manager.mojom.h"
 #include "mojo/public/cpp/application/application.h"
 #include "mojo/services/public/cpp/view_manager/node.h"
@@ skipping 98 matching lines @@
   }
 
     // Overridden from ViewObserver:
   virtual void OnViewInputEvent(View* view, const EventPtr& event) OVERRIDE {
     if (event->action == ui::ET_MOUSE_RELEASED) {
       std::string app_url;
       if (event->flags & ui::EF_LEFT_MOUSE_BUTTON)
         app_url = "mojo://mojo_embedded_app";
       else if (event->flags & ui::EF_RIGHT_MOUSE_BUTTON)
         app_url = "mojo://mojo_nesting_app";
-      DCHECK(!app_url.empty());
+      if (app_url.empty())
+        return;
 
       Node* node = view_manager_->GetNodeById(parent_node_id_);
       navigation::NavigationDetailsPtr nav_details(
           navigation::NavigationDetails::New());
       size_t index = node->children().size() - 1;
       nav_details->url = base::StringPrintf(
           "%s/%x", app_url.c_str(), kColors[index % arraysize(kColors)]);
       navigation::ResponseDetailsPtr response;
       CreateWindow(app_url, nav_details.Pass(), response.Pass());
     }
@@ skipping 86 matching lines @@
 }
 
 }  // namespace examples
 
 // static
 Application* Application::Create() {
   return new examples::WindowManager;
 }
 
 }  // namespace mojo