Don't call WebContents::DownloadImage() callback if the WebContents were deleted

content/browser/web_contents/web_contents_impl.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 CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 800 matching lines @@
   void AddDestructionObserver(WebContentsImpl* web_contents);
 
   // Deletes and removes from the map a destruction observer
   // watching |web_contents|. No-op if there is no such observer.
   void RemoveDestructionObserver(WebContentsImpl* web_contents);
 
   // Traverses all the RenderFrameHosts in the FrameTree and creates a set
   // all the unique RenderWidgetHostViews.
   std::set<RenderWidgetHostView*> GetRenderWidgetHostViewsInTree();
 
+  // Called with the result of a DownloadImage() request.
+  void OnDidDownloadImage(const ImageDownloadCallback& callback,
+                          int id,
+                          const GURL& image_url,
+                          image_downloader::DownloadResultPtr result);
+
   // Callback function when showing JavaScript dialogs.  Takes in a routing ID
   // pair to identify the RenderFrameHost that opened the dialog, because it's
   // possible for the RenderFrameHost to be deleted by the time this is called.
   void OnDialogClosed(int render_process_id,
                       int render_frame_id,
                       IPC::Message* reply_msg,
                       bool dialog_was_suppressed,
                       bool success,
                       const base::string16& user_input);
 
@@ skipping 469 matching lines @@
 
   // Manages media players, CDMs, and power save blockers for media.
   scoped_ptr<MediaWebContentsObserver> media_web_contents_observer_;
 
   scoped_ptr<RenderWidgetHostInputEventRouter> rwh_input_event_router_;
 
   PageImportanceSignals page_importance_signals_;
 
   bool page_scale_factor_is_one_;
 
+  base::WeakPtrFactory<WebContentsImpl> download_image_weak_factory_;

[jam, 2016/02/12 23:31:42]

since this is never reset, just make this be weak_factory_ so that if other code
needs it they can use it.

   base::WeakPtrFactory<WebContentsImpl> loading_weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsImpl);
 };
 
 // Dangerous methods which should never be made part of the public API, so we
 // grant their use only to an explicit friend list (c++ attorney/client idiom).
 class CONTENT_EXPORT WebContentsImpl::FriendZone {
  private:
   friend class TestNavigationObserver;
   friend class WebContentsAddedObserver;
   friend class ContentBrowserSanityChecker;
 
   FriendZone();  // Not instantiable.
 
   // Adds/removes a callback called on creation of each new WebContents.
   static void AddCreatedCallbackForTesting(const CreatedCallback& callback);
   static void RemoveCreatedCallbackForTesting(const CreatedCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(FriendZone);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_