Don't crash after calling frame_->stopLoading().

content/renderer/render_frame_impl.cc

 // Copyright 2013 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 "content/renderer/render_frame_impl.h"
 
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 4482 matching lines @@
 }
 
 void RenderFrameImpl::RemoveObserver(RenderFrameObserver* observer) {
   observer->RenderFrameGone();
   observers_.RemoveObserver(observer);
 }
 
 void RenderFrameImpl::OnStop() {
   DCHECK(frame_);
   frame_->stopLoading();
-  if (!frame_->parent())
+  if (frame_ && !frame_->parent())
     FOR_EACH_OBSERVER(RenderViewObserver, render_view_->observers_, OnStop());
 
   FOR_EACH_OBSERVER(RenderFrameObserver, observers_, OnStop());
 }
 
 void RenderFrameImpl::WasHidden() {
   FOR_EACH_OBSERVER(RenderFrameObserver, observers_, WasHidden());
 
 #if defined(ENABLE_PLUGINS)
   for (auto* plugin : active_pepper_instances_)
@@ skipping 1132 matching lines @@
         return;
     }
   } else {
     // The browser expects the frame to be loading this navigation. Inform it
     // that the load stopped if needed.
     // Note: in the case of history navigations, |should_load_request| will be
     // false, and the frame may not have been set in a loading state. Do not
     // send a stop message if the HistoryController is loading in this frame
     // nonetheless. This behavior will go away with subframe navigation
     // entries.
-    if (!frame_->isLoading() && !has_history_navigation_in_frame)
+    if (frame_ && !frame_->isLoading() && !has_history_navigation_in_frame)
       Send(new FrameHostMsg_DidStopLoading(routing_id_));
   }
 
   // In case LoadRequest failed before didCreateDataSource was called.
   pending_navigation_params_.reset();
 }
 
 void RenderFrameImpl::UpdateEncoding(WebFrame* frame,
                                      const std::string& encoding_name) {
   // Only update main frame's encoding_name.
@@ skipping 683 matching lines @@
   // event target. Potentially a Pepper plugin will receive the event.
   // In order to tell whether a plugin gets the last mouse event and which it
   // is, we set |pepper_last_mouse_event_target_| to null here. If a plugin gets
   // the event, it will notify us via DidReceiveMouseEvent() and set itself as
   // |pepper_last_mouse_event_target_|.
   pepper_last_mouse_event_target_ = nullptr;
 #endif
 }
 
 }  // namespace content