Fix resize ACK bug

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 717e2c018b2c4ddfe192486aeae42725c7c26fda..a130030e9bf9c0372dbc07162ca1f7319c02b595 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -591,7 +591,7 @@ bool RenderWidgetHostImpl::GetResizeParams(
 
   const bool size_changed =
       !old_resize_params_ ||
-      old_resize_params_->new_size != resize_params->new_size;
+      current_size_ != resize_params->new_size;
   bool dirty =
       size_changed || screen_info_out_of_date_ ||
       old_resize_params_->physical_backing_size !=
@@ -638,6 +638,9 @@ void RenderWidgetHostImpl::WasResized() {
       old_resize_params_->new_size.width() != params->new_size.width();
   if (Send(new ViewMsg_Resize(routing_id_, *params))) {
     resize_ack_pending_ = params->needs_resize_ack;
+    DCHECK_IMPLIES(params->new_size.IsEmpty(), !params->needs_resize_ack);
+    if (params->new_size.IsEmpty())

[no sievers, 2015/02/26 00:23:06]

This is purely to make one of the tests happy which verifies that setting the
bounds to the same empty rect repeatedly does not send redundant updates.

I went back and forth on this :)
So we could also set |current_size_| to |new_size| here always if
|!needs_resize_ack|. But then we would end up skipping the ack for the case I
was originally trying to address, i.e. when the view bounds are already nonzero
and physical backing size becomes nonzero. Since that implies a paint it's maybe
better to throttle then.

+      current_size_ = params->new_size;
     old_resize_params_.swap(params);
   }