Fix resize issues when using threaded compositing

content/browser/renderer_host/render_widget_host.cc

 // Copyright (c) 2011 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/browser/renderer_host/render_widget_host.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 975 matching lines @@
   }
 
   bool is_repaint_ack =
       ViewHostMsg_UpdateRect_Flags::is_repaint_ack(params.flags);
   if (is_repaint_ack) {
     repaint_ack_pending_ = false;
     TimeDelta delta = TimeTicks::Now() - repaint_start_time_;
     UMA_HISTOGRAM_TIMES("MPArch.RWH_RepaintDelta", delta);
   }
 
-  DCHECK(!params.bitmap_rect.IsEmpty());
   DCHECK(!params.view_size.IsEmpty());
 
   bool was_async = false;
   if (!is_accelerated_compositing_active_) {
+    DCHECK(!params.bitmap_rect.IsEmpty());
     const size_t size = params.bitmap_rect.height() *
         params.bitmap_rect.width() * 4;
     TransportDIB* dib = process_->GetTransportDIB(params.bitmap);
 
     // If gpu process does painting, scroll_rect and copy_rects are always empty
     // and backing store is never used.
     if (dib) {
       if (dib->size() < size) {
         DLOG(WARNING) << "Transport DIB too small for given rectangle";
         UserMetrics::RecordAction(
@@ skipping 458 matching lines @@
     pending_mouse_lock_request_ = false;
     if (!view_ || !view_->HasFocus()|| !view_->LockMouse()) {
       Send(new ViewMsg_LockMouse_ACK(routing_id_, false));
       return false;
     } else {
       Send(new ViewMsg_LockMouse_ACK(routing_id_, true));
       return true;
     }
   }
 }