Remove unused/unnecessary code from the external protocol dialog for ARC

chrome/browser/chromeos/arc/arc_external_protocol_dialog.cc

 // Copyright 2016 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/chromeos/arc/arc_external_protocol_dialog.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 57 matching lines @@
                           size_t selected_app_index,
                           ArcNavigationThrottle::CloseReason close_reason) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   mojom::IntentHelperInstance* intent_helper = GetIntentHelper();
   if (!intent_helper || selected_app_index >= handlers.size())
     close_reason = ArcNavigationThrottle::CloseReason::ERROR;
 
   switch (close_reason) {
     case ArcNavigationThrottle::CloseReason::ALWAYS_PRESSED: {
-      intent_helper->AddPreferredPackage(
-          handlers[selected_app_index]->package_name);
-      // fall through.
+      // TODO(yusukes): Add NOTREACHED(); break; here once b/31665510 is fixed.
+      // fall through, for now.
     }
-    case ArcNavigationThrottle::CloseReason::JUST_ONCE_PRESSED:
-    case ArcNavigationThrottle::CloseReason::PREFERRED_ACTIVITY_FOUND: {
+    case ArcNavigationThrottle::CloseReason::JUST_ONCE_PRESSED: {
       // Launch the selected app.
       intent_helper->HandleUrl(url.spec(),
                                handlers[selected_app_index]->package_name);
       CloseTabIfNeeded(render_process_host_id, routing_id);
       break;
     }
+    case ArcNavigationThrottle::CloseReason::PREFERRED_ACTIVITY_FOUND: {
+      // Our OnUrlHandlerList callback does not search for a preferred activity.
+      NOTREACHED();
+      break;
+    }
     case ArcNavigationThrottle::CloseReason::ERROR:
     case ArcNavigationThrottle::CloseReason::INVALID: {
       LOG(ERROR) << "IntentPickerBubbleView returned unexpected close_reason: "
                  << static_cast<int>(close_reason);
       // fall through.
     }
     case ArcNavigationThrottle::CloseReason::DIALOG_DEACTIVATED: {
       // The user didn't select any ARC activity. Show the Chrome OS dialog.
       ShowFallbackExternalProtocolDialog(render_process_host_id, routing_id,
                                          url);
@@ skipping 79 matching lines @@
 
   // Show ARC version of the dialog, which is IntentPickerBubbleView. To show
   // the bubble view, we need to ask ARC for a handler list first.
   intent_helper->RequestUrlHandlerList(
       url.spec(),
       base::Bind(OnUrlHandlerList, render_process_host_id, routing_id, url));
   return true;
 }
 
 }  // namespace arc