Use a const reference in IntentPickerResponse

chrome/browser/ui/views/intent_picker_bubble_view_unittest.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/ui/views/intent_picker_bubble_view.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 49 matching lines @@
   }
 
   void FillAppListWithDummyIcons() {
     ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
     gfx::Image dummy_icon = rb.GetImageNamed(IDR_CLOSE);
     for (auto& app : app_info_)
       app.icon = dummy_icon;
   }
 
   // Dummy method to be called upon bubble closing.
-  void OnBubbleClosed(std::string selected_app_package,
+  void OnBubbleClosed(const std::string& selected_app_package,
                       arc::ArcNavigationThrottle::CloseReason close_reason) {}
 
   std::unique_ptr<IntentPickerBubbleView> bubble_;
   std::vector<AppInfo> app_info_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(IntentPickerBubbleViewTest);
 };
 
 // Verifies that we didn't set up an image for any LabelButton.
@@ skipping 56 matching lines @@
   const ui::MouseEvent event(ui::ET_MOUSE_PRESSED, gfx::Point(), gfx::Point(),
                              ui::EventTimeForNow(), 0, 0);
   EXPECT_EQ(bubble_->GetInkDropStateForTesting(0), views::InkDropState::HIDDEN);
   bubble_->PressButtonForTesting(0, event);
   EXPECT_EQ(bubble_->GetInkDropStateForTesting(0),
             views::InkDropState::ACTIVATED);
   bubble_->PressButtonForTesting(0, event);
   EXPECT_EQ(bubble_->GetInkDropStateForTesting(0),
             views::InkDropState::ACTIVATED);
 }