Added DCHECK() to prevent webwidget_->isInputThrottled() from being called when webwidget_ is NULL.

content/renderer/render_widget.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/render_widget.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 565 matching lines @@
     suppress_next_char_events_ = true;
 
   IPC::Message* response =
       new ViewHostMsg_HandleInputEvent_ACK(routing_id_, input_event->type,
                                            processed);
   bool event_type_gets_rate_limited =
       input_event->type == WebInputEvent::MouseMove ||
       input_event->type == WebInputEvent::MouseWheel ||
       WebInputEvent::isTouchEventType(input_event->type);
   bool is_input_throttled =
-      webwidget_->isInputThrottled() ||
+      (webwidget_ ? webwidget_->isInputThrottled() : false) ||
       paint_aggregator_.HasPendingUpdate();
 
   if (event_type_gets_rate_limited && is_input_throttled && !is_hidden_) {
     // We want to rate limit the input events in this case, so we'll wait for
     // painting to finish before ACKing this message.
     if (pending_input_event_ack_.get()) {
       // As two different kinds of events could cause us to postpone an ack
       // we send it now, if we have one pending. The Browser should never
       // send us the same kind of event we are delaying the ack for.
       Send(pending_input_event_ack_.release());
@@ skipping 1176 matching lines @@
   Send(new ViewHostMsg_BeginSmoothScroll(routing_id_, down, scroll_far));
 }
 
 bool RenderWidget::WillHandleMouseEvent(const WebKit::WebMouseEvent& event) {
   return false;
 }
 
 bool RenderWidget::WebWidgetHandlesCompositorScheduling() const {
   return false;
 }