Fix race between DPI and window size

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 73652f023e27f3afed577d177ab2df14383d8a33..dd168621d4ccf389242146788fb609cd07b9e8f4 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -147,6 +147,7 @@ RenderWidgetHostImpl::RenderWidgetHostImpl(RenderWidgetHostDelegate* delegate,
       is_accelerated_compositing_active_(false),
       repaint_ack_pending_(false),
       resize_ack_pending_(false),
+      renderer_screen_info_out_of_date_(false),
       overdraw_bottom_height_(0.f),
       should_auto_resize_(false),
       waiting_for_screen_rects_ack_(false),
@@ -526,6 +527,7 @@ void RenderWidgetHostImpl::WasResized() {
 
   bool size_changed = new_size != current_size_;
   bool side_payload_changed =
+      renderer_screen_info_out_of_date_ ||
       old_physical_backing_size != physical_backing_size_ ||
       was_fullscreen != is_fullscreen_ ||
       old_overdraw_bottom_height != overdraw_bottom_height_;
@@ -542,12 +544,18 @@ void RenderWidgetHostImpl::WasResized() {
   if (!new_size.IsEmpty() && !physical_backing_size_.IsEmpty() && size_changed)
     resize_ack_pending_ = true;
 
-  if (!Send(new ViewMsg_Resize(routing_id_, new_size, physical_backing_size_,
-                               overdraw_bottom_height_,
-                               GetRootWindowResizerRect(), is_fullscreen_))) {
+  ViewMsg_Resize_Params params;
+  GetWebScreenInfo(&params.screen_info);

[piman, 2013/05/25 00:37:25]

This could be a bit expensive, like round-tripping to X on linux, but done on
every resize. Could we still query it in NotifyScreenInfoChanged which should
only happen rarely, and cache it as a field?

[ccameron, 2013/05/25 01:53:37]

Yes, I was on the fence about this. I didn't initially put it in because of the
include order issue. I've updated this to have a scoped_ptr<> which is reset
when it becomes invalid.

+  params.new_size = new_size;
+  params.physical_backing_size = physical_backing_size_;
+  params.overdraw_bottom_height = overdraw_bottom_height_;
+  params.resizer_rect = GetRootWindowResizerRect();
+  params.is_fullscreen = is_fullscreen_;
+  if (!Send(new ViewMsg_Resize(routing_id_, params))) {
     resize_ack_pending_ = false;
   } else {
     in_flight_size_ = new_size;
+    renderer_screen_info_out_of_date_ = false;
   }
 }
 
@@ -1333,9 +1341,11 @@ const NativeWebKeyboardEvent*
 }
 
 void RenderWidgetHostImpl::NotifyScreenInfoChanged() {
-  WebKit::WebScreenInfo screen_info;
-  GetWebScreenInfo(&screen_info);
-  Send(new ViewMsg_ScreenInfoChanged(GetRoutingID(), screen_info));
+  // The resize message (which may not happen immediately) will carry with it
+  // the screen info as well as the new size (if the screen has changed scale
+  // factor).
+  renderer_screen_info_out_of_date_ = true;
+  WasResized();
 }
 
 void RenderWidgetHostImpl::GetSnapshotFromRenderer(