3 files changed, 32 insertions, 9 deletions
diff --git a/components/script/dom/htmliframeelement.rs b/components/script/dom/htmliframeelement.rs
index f5a820458c2..e58e65ea5bb 100644
--- a/components/script/dom/htmliframeelement.rs
+++ b/components/script/dom/htmliframeelement.rs
@@ -28,7 +28,6 @@ use crate::dom::windowproxy::WindowProxy;
 use crate::script_thread::ScriptThread;
 use crate::task_source::TaskSource;
 use dom_struct::dom_struct;
-use euclid::Size2D;
 use html5ever::{LocalName, Prefix};
 use ipc_channel::ipc;
 use msg::constellation_msg::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
@@ -173,6 +172,13 @@ impl HTMLIFrameElement {
             replace: replace,
         };
 
+        let window_size = WindowSizeData {
+            initial_viewport: window
+                .inner_window_dimensions_query(browsing_context_id)
+                .unwrap_or_default(),
+            device_pixel_ratio: window.device_pixel_ratio(),
+        };
+
         match nav_type {
             NavigationType::InitialAboutBlank => {
                 let (pipeline_sender, pipeline_receiver) = ipc::channel().unwrap();
@@ -184,6 +190,7 @@ impl HTMLIFrameElement {
                     load_data: load_data.clone(),
                     old_pipeline_id: old_pipeline_id,
                     sandbox: sandboxed,
+                    window_size,
                 };
                 global_scope
                     .script_to_constellation_chan()
@@ -198,13 +205,7 @@ impl HTMLIFrameElement {
                     opener: None,
                     load_data: load_data,
                     pipeline_port: pipeline_receiver,
-                    window_size: WindowSizeData {
-                        initial_viewport: {
-                            let rect = self.upcast::<Node>().bounding_content_box_or_zero();
-                            Size2D::new(rect.size.width.to_f32_px(), rect.size.height.to_f32_px())
-                        },
-                        device_pixel_ratio: window.device_pixel_ratio(),
-                    },
+                    window_size,
                 };
 
                 self.pipeline_id.set(Some(new_pipeline_id));
@@ -216,6 +217,7 @@ impl HTMLIFrameElement {
                     load_data: load_data,
                     old_pipeline_id: old_pipeline_id,
                     sandbox: sandboxed,
+                    window_size,
                 };
                 global_scope
                     .script_to_constellation_chan()
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 70099ee5866..95326b46352 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -89,7 +89,7 @@ use js::jsval::{JSVal, NullValue};
 use js::rust::wrappers::JS_DefineProperty;
 use js::rust::{CustomAutoRooter, CustomAutoRooterGuard, HandleValue};
 use media::WindowGLContext;
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image_cache::{ImageCache, ImageResponder, ImageResponse};
 use net_traits::image_cache::{PendingImageId, PendingImageResponse};
 use net_traits::storage_thread::StorageType;
@@ -1829,6 +1829,16 @@ impl Window {
         DOMString::from(resolved)
     }
 
+    pub fn inner_window_dimensions_query(
+        &self,
+        browsing_context: BrowsingContextId,
+    ) -> Option<Size2D<f32, CSSPixel>> {
+        if !self.layout_reflow(QueryMsg::InnerWindowDimensionsQuery(browsing_context)) {
+            return None;
+        }
+        self.layout_rpc.inner_window_dimensions()
+    }
+
     #[allow(unsafe_code)]
     pub fn offset_parent_query(&self, node: &Node) -> (Option<DomRoot<Element>>, UntypedRect<Au>) {
         if !self.layout_reflow(QueryMsg::OffsetParentQuery(node.to_opaque())) {
@@ -2359,6 +2369,7 @@ fn debug_reflow_events(id: PipelineId, reflow_goal: &ReflowGoal, reason: &Reflow
             &QueryMsg::StyleQuery(_n) => "\tStyleQuery",
             &QueryMsg::TextIndexQuery(..) => "\tTextIndexQuery",
             &QueryMsg::ElementInnerTextQuery(_) => "\tElementInnerTextQuery",
+            &QueryMsg::InnerWindowDimensionsQuery(_) => "\tInnerWindowDimensionsQuery",
         },
     });
 
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 6a7a69651e7..191df335ec5 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -2392,6 +2392,7 @@ impl ScriptThread {
                 load_data.url.clone(),
             ),
             layout_is_busy: layout_is_busy.clone(),
+            window_size,
         });
 
         // Pick a layout thread, any layout thread
@@ -3696,6 +3697,15 @@ impl ScriptThread {
         };
 
         let window = document.window();
+        if window.window_size() == new_size {
+            return;
+        }
+        debug!(
+            "resizing pipeline {:?} from {:?} to {:?}",
+            pipeline_id,
+            window.window_size(),
+            new_size
+        );
         window.set_window_size(new_size);
         window.force_reflow(ReflowGoal::Full, ReflowReason::WindowResize);