Fixed crash if tab closes while WebShare picker dialog is open.

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 30 matching lines @@
   joined_pieces.reserve(total_size);
 
   for (const auto& piece : pieces) {
     piece.AppendToString(&joined_pieces);
   }
   return joined_pieces;
 }
 
 }  // namespace
 
-ShareServiceImpl::ShareServiceImpl() = default;
+ShareServiceImpl::ShareServiceImpl() : weak_factory_(this) {}
 ShareServiceImpl::~ShareServiceImpl() = default;
 
 // static
 void ShareServiceImpl::Create(blink::mojom::ShareServiceRequest request) {
   mojo::MakeStrongBinding(base::MakeUnique<ShareServiceImpl>(),
                           std::move(request));
 }
 
 // static
 bool ShareServiceImpl::ReplacePlaceholders(base::StringPiece url_template,
@@ skipping 134 matching lines @@
 
   share_targets = GetPrefService()
                       ->GetDictionary(prefs::kWebShareVisitedTargets)
                       ->CreateDeepCopy();
 
   std::vector<std::pair<base::string16, GURL>> sufficiently_engaged_targets =
       GetTargetsWithSufficientEngagement(*share_targets);
 
   ShowPickerDialog(
       sufficiently_engaged_targets,
-      base::Bind(&ShareServiceImpl::OnPickerClosed, base::Unretained(this),
+      base::Bind(&ShareServiceImpl::OnPickerClosed, weak_factory_.GetWeakPtr(),
                  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,
@@ skipping 22 matching lines @@
   const GURL target(url_base.as_string() + url_template_filled);
   if (!target.is_valid()) {
     callback.Run(base::Optional<std::string>(
         "Error: url of share target is not a valid url."));
     return;
   }
   OpenTargetURL(target);
 
   callback.Run(base::nullopt);
 }