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

chrome/browser/webshare/share_service_impl.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/webshare/share_service_impl.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 
@@ skipping 86 matching lines @@
   }
   split_template.push_back(url_template.substr(
       start_index_to_copy, url_template.size() - start_index_to_copy));
 
   *url_template_filled = base::JoinString(split_template, base::StringPiece());
   return true;
 }
 
 void ShareServiceImpl::ShowPickerDialog(
     const std::vector<std::pair<base::string16, GURL>>& targets,
-    const base::Callback<void(base::Optional<std::string>)>& callback) {
-// TODO(mgiuca): Get the browser window as |parent_window|.
+    const chrome::WebShareTargetPickerCallback& callback) {
+  // TODO(mgiuca): Get the browser window as |parent_window|.
   chrome::ShowWebShareTargetPickerDialog(nullptr /* parent_window */, targets,
                                          callback);
 }
 
 Browser* ShareServiceImpl::GetBrowser() {
   return BrowserList::GetInstance()->GetLastActive();
 }
 
 void ShareServiceImpl::OpenTargetURL(const GURL& target_url) {
   Browser* browser = GetBrowser();
@@ skipping 71 matching lines @@
                  base::Passed(&share_targets), title, text, share_url,
                  callback));
 }
 
 void ShareServiceImpl::OnPickerClosed(
     std::unique_ptr<base::DictionaryValue> share_targets,
     const std::string& title,
     const std::string& text,
     const GURL& share_url,
     const ShareCallback& callback,
-    base::Optional<std::string> result) {
+    const base::Optional<std::string>& result) {
   if (!result.has_value()) {
     callback.Run(blink::mojom::ShareError::CANCELED);
     return;
   }
 
   std::string chosen_target = result.value();
 
   std::string url_template = GetTargetTemplate(chosen_target, *share_targets);
   std::string url_template_filled;
   if (!ReplacePlaceholders(url_template, title, text, share_url,
@@ skipping 15 matching lines @@
   // - The base URL: can't be invalid since it's derived from the manifest URL.
   // - The template: can only be invalid if it contains a NUL character or
   //   invalid UTF-8 sequence (which it can't have).
   // - The replaced pieces: these are escaped.
   // If somehow we slip through this DCHECK, it will just open about:blank.
   DCHECK(target.is_valid());
   OpenTargetURL(target);
 
   callback.Run(blink::mojom::ShareError::OK);
 }