webshare: Small refactor of WebShare (OnceCallback, const&, and alias)

chrome/browser/ui/views/webshare/webshare_target_picker_view_unittest.cc

 // Copyright 2017 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/webshare/webshare_target_picker_view.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 43 matching lines @@
     quit_closure_ = base::Closure();
     constrained_window::SetConstrainedWindowViewsClient(nullptr);
 
     ViewsTestBase::TearDown();
   }
 
  protected:
   // Creates the WebShareTargetPickerView (available as view()).
   void CreateView(const std::vector<std::pair<base::string16, GURL>>& targets) {
     view_ = new WebShareTargetPickerView(
-        targets, base::Bind(&WebShareTargetPickerViewTest::OnCallback,
-                            base::Unretained(this)));
+        targets, base::BindOnce(&WebShareTargetPickerViewTest::OnCallback,
+                                base::Unretained(this)));
     constrained_window::CreateBrowserModalDialogViews(
         view_, parent_widget_->GetNativeWindow())
         ->Show();
   }
 
   // Sets the closure that will be called when the dialog is closed. This is
   // used in tests to quit the RunLoop.
   void SetQuitClosure(base::Closure&& quit_closure) {
     quit_closure_ = std::move(quit_closure);
   }
 
   // The view under test.
   WebShareTargetPickerView* view() { return view_; }
   // The table inside the view (for inspection).
   views::TableView* table() { return view_->table_; }
 
   // The result that was returned to the dialog's callback.
   const base::Optional<std::string>& result() { return result_; }
 
  private:
-  void OnCallback(base::Optional<std::string> result) {
+  void OnCallback(const base::Optional<std::string>& result) {
     result_ = result;
     if (quit_closure_)
       quit_closure_.Run();
   }
 
   std::unique_ptr<views::Widget> parent_widget_;
   WebShareTargetPickerView* view_ = nullptr;
 
   base::Optional<std::string> result_;
 
@@ skipping 67 matching lines @@
   base::RunLoop run_loop;
   SetQuitClosure(run_loop.QuitClosure());
 
   view()->OnDoubleClick();
 
   run_loop.Run();
 
   EXPECT_EQ(base::Optional<std::string>("https://appone.com/path/bits"),
             result());
 }