Prevent browser thumbnailer from trying to read from frontbuffer (surface texture) when none exists.

content/browser/renderer_host/render_widget_host_view_gtk.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_view_gtk.h"
 
 // If this gets included after the gtk headers, then a bunch of compiler
 // errors happen because of a "#define Status int" in Xlib.h, which interacts
 // badly with net::URLRequestStatus::Status.
 #include "content/common/view_messages.h"
@@ skipping 716 matching lines @@
 void RenderWidgetHostViewGtk::Blur() {
   // TODO(estade): We should be clearing native focus as well, but I know of no
   // way to do that without focusing another widget.
   host_->Blur();
 }
 
 bool RenderWidgetHostViewGtk::HasFocus() const {
   return gtk_widget_is_focus(view_.get());
 }
 
+bool RenderWidgetHostViewGtk::HasSurface() const {
+  return false;

[mazda, 2012/05/03 19:57:31]

return !!host_->GetBackingStore(false);

+}
+
 void RenderWidgetHostViewGtk::Show() {
   gtk_widget_show(view_.get());
 }
 
 void RenderWidgetHostViewGtk::Hide() {
   gtk_widget_hide(view_.get());
 }
 
 bool RenderWidgetHostViewGtk::IsShowing() {
   return gtk_widget_get_visible(view_.get());
@@ skipping 650 matching lines @@
   return new RenderWidgetHostViewGtk(widget);
 }
 
 // static
 void content::RenderWidgetHostViewPort::GetDefaultScreenInfo(
     WebKit::WebScreenInfo* results) {
   GdkWindow* gdk_window =
       gdk_display_get_default_group(gdk_display_get_default());
   content::GetScreenInfoFromNativeWindow(gdk_window, results);
 }