Don't expect ack for ViewMsg_OnResize if backing size is empty

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index d0a2d5c2b90c24eda25729b3effcf5d8f86400ca..9296c67ac42dc5e6e71345c5525c1ecfa8ef28aa 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -511,9 +511,9 @@ void RenderWidgetHostImpl::WasResized() {
       !side_payload_changed)
     return;
 
-  // We don't expect to receive an ACK when the requested size is empty or when
-  // the main viewport size didn't change.
-  if (!new_size.IsEmpty() && size_changed)
+  // We don't expect to receive an ACK when the requested size or the physical
+  // backing size is empty or when the main viewport size didn't change.
+  if (!new_size.IsEmpty() && !physical_backing_size_.IsEmpty() && size_changed)

[piman, 2013/05/10 20:12:06]

I don't see a corresponding test in RenderWidget::Resize. I think the renderer
will send you an ack anyway, and things will be confused.

[Xianzhu, 2013/05/10 20:25:03]

We have tested that the renderer doesn't send ack when physical_backing_size is
empty (which seems to only happen on Android).

render_widget_host_unittests.cc lines 883-891 are testing the case. Is that
enough?

     resize_ack_pending_ = true;
 
   if (!Send(new ViewMsg_Resize(routing_id_, new_size, physical_backing_size_,