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

content/browser/renderer_host/test_render_view_host.cc

Index: content/browser/renderer_host/test_render_view_host.cc
diff --git a/content/browser/renderer_host/test_render_view_host.cc b/content/browser/renderer_host/test_render_view_host.cc
index 44423f7a4b8b86f5dabc903415f3164e1d333063..d5bb8dee0eb84657b4644739e211b4e707789448 100644
--- a/content/browser/renderer_host/test_render_view_host.cc
+++ b/content/browser/renderer_host/test_render_view_host.cc
@@ -68,6 +68,10 @@ bool TestRenderWidgetHostView::HasFocus() const {
   return true;
 }
 
+bool TestRenderWidgetHostView::HasSurface() const {
+  return false;
+}
+
 void TestRenderWidgetHostView::Show() {
   is_showing_ = true;
 }