Don't try to access a NULL plugin element or document in PepperPluginInstanceImpl

content/renderer/pepper/pepper_plugin_instance_impl.cc

 // 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.
 
 #include "content/renderer/pepper/pepper_plugin_instance_impl.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 655 matching lines @@
 v8::Local<v8::Object> PepperPluginInstanceImpl::GetMessageChannelObject() {
   return v8::Local<v8::Object>::New(isolate_, message_channel_object_);
 }
 
 void PepperPluginInstanceImpl::MessageChannelDestroyed() {
   message_channel_ = NULL;
   message_channel_object_.Reset();
 }
 
 v8::Local<v8::Context> PepperPluginInstanceImpl::GetContext() {
-  if (!container_)
+  if (!container_ ||
+      container_->element().isNull() ||
+      container_->element().document().isNull() ||
+      !container_->element().document().frame()) {
     return v8::Handle<v8::Context>();
-  WebLocalFrame* frame = container_->element().document().frame();
-  if (!frame)
-    return v8::Handle<v8::Context>();
+  }
 
-  v8::Local<v8::Context> context = frame->mainWorldScriptContext();
+  v8::Local<v8::Context> context =
+      container_->element().document().frame()->mainWorldScriptContext();
   DCHECK(context->GetIsolate() == isolate_);
   return context;
 }
 
 void PepperPluginInstanceImpl::Delete() {
   is_deleted_ = true;
 
   if (render_frame_ &&
       render_frame_->render_view()->plugin_find_handler() == this) {
     render_frame_->render_view()->set_plugin_find_handler(NULL);
@@ skipping 2672 matching lines @@
     // Running out-of-process. Initiate an IPC call to notify the plugin
     // process.
     ppapi::proxy::HostDispatcher* dispatcher =
         ppapi::proxy::HostDispatcher::GetForInstance(pp_instance());
     dispatcher->Send(new PpapiMsg_PPPInstance_HandleDocumentLoad(
         ppapi::API_ID_PPP_INSTANCE, pp_instance(), pending_host_id, data));
   }
 }
 
 }  // namespace content