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

chrome/browser/ui/browser_dialogs.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_BROWSER_DIALOGS_H_
 #define CHROME_BROWSER_UI_BROWSER_DIALOGS_H_
 
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 139 matching lines @@
 
 // Shows the toolkit-views based BookmarkEditor.
 void ShowBookmarkEditorViews(gfx::NativeWindow parent_window,
                              Profile* profile,
                              const BookmarkEditor::EditDetails& details,
                              BookmarkEditor::Configuration configuration);
 
 payments::PaymentRequestDialog* CreatePaymentRequestDialog(
     payments::PaymentRequest* request);
 
+// Used to return the target the user picked or nullopt if the user cancelled
+// the share.
+using WebShareTargetPickerCallback =
+    base::OnceCallback<void(const base::Optional<std::string>&)>;

[Matt Giuca, 2017/05/01 23:15:33]

nit: Blank line between.

 // Shows the dialog to choose a share target app. |targets| is a list of app
 // title and manifest URL pairs that will be shown in a list. If the user picks
 // a target, this calls |callback| with the manifest URL of the chosen target,
 // or supplies null if the user cancelled the share.
 void ShowWebShareTargetPickerDialog(
     gfx::NativeWindow parent_window,
     const std::vector<std::pair<base::string16, GURL>>& targets,
-    const base::Callback<void(base::Optional<std::string>)>& callback);
+    WebShareTargetPickerCallback callback);
 
 #if defined(OS_MACOSX)
 
 // This is a class so that it can be friended from ContentSettingBubbleContents,
 // which allows it to call SetAnchorRect().
 class ContentSettingBubbleViewsBridge {
  public:
   static void Show(gfx::NativeView parent_view,
                    ContentSettingBubbleModel* model,
                    content::WebContents* web_contents,
@@ skipping 71 matching lines @@
 using BubbleShowPtr =
     void (*)(content::WebContents*,
              const std::vector<arc::ArcNavigationThrottle::AppInfo>&,
              const IntentPickerResponse&);
 
 BubbleShowPtr ShowIntentPickerBubble();
 
 #endif  // OS_CHROMEOS
 
 #endif  // CHROME_BROWSER_UI_BROWSER_DIALOGS_H_