Fix resize ACK bug

content/browser/renderer_host/render_widget_host_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/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 #include <set>
 #include <utility>
 
@@ skipping 573 matching lines @@
     resize_params->physical_backing_size = view_->GetPhysicalBackingSize();
     resize_params->top_controls_height = view_->GetTopControlsHeight();
     resize_params->top_controls_shrink_blink_size =
         view_->DoTopControlsShrinkBlinkSize();
     resize_params->visible_viewport_size = view_->GetVisibleViewportSize();
     resize_params->is_fullscreen = IsFullscreen();
   }
 
   const bool size_changed =
       !old_resize_params_ ||
-      old_resize_params_->new_size != resize_params->new_size;
+      old_resize_params_->new_size != resize_params->new_size ||
+      (old_resize_params_->physical_backing_size.IsEmpty() &&
+       !resize_params->physical_backing_size.IsEmpty());
   bool dirty =
       size_changed || screen_info_out_of_date_ ||
       old_resize_params_->physical_backing_size !=
           resize_params->physical_backing_size ||
       old_resize_params_->is_fullscreen != resize_params->is_fullscreen ||
       old_resize_params_->top_controls_height !=
           resize_params->top_controls_height ||
       old_resize_params_->top_controls_shrink_blink_size !=
           resize_params->top_controls_shrink_blink_size ||
       old_resize_params_->visible_viewport_size !=
@@ skipping 1586 matching lines @@
 }
 #endif
 
 SkColorType RenderWidgetHostImpl::PreferredReadbackFormat() {
   if (view_)
     return view_->PreferredReadbackFormat();
   return kN32_SkColorType;
 }
 
 }  // namespace content