The constellation notifies the script thread about documents becoming inactive, active and fully active.

components/constellation/constellation.rs

@@ -95,7 +95,7 @@ use profile_traits::mem;
 use profile_traits::time;
 use script_traits::{AnimationState, AnimationTickType, CompositorEvent};
 use script_traits::{ConstellationControlMsg, ConstellationMsg as FromCompositorMsg, DiscardBrowsingContext};
-use script_traits::{DocumentState, LayoutControlMsg, LoadData};
+use script_traits::{DocumentActivity, DocumentState, LayoutControlMsg, LoadData};
 use script_traits::{IFrameLoadInfo, IFrameLoadInfoWithData, IFrameSandboxState, TimerEventRequest};
 use script_traits::{LayoutMsg as FromLayoutMsg, ScriptMsg as FromScriptMsg, ScriptThreadFactory};
 use script_traits::{LogEntry, ServiceWorkerMsg, webdriver_msg};
@@ -1405,10 +1405,6 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
 
             let window_size = old_pipeline.and_then(|old_pipeline| old_pipeline.size);
 
-            if let Some(old_pipeline) = old_pipeline {
-                old_pipeline.freeze();
-            }
-
             (load_data, window_size, is_private)
         };
 
@@ -1628,11 +1624,6 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 });
                 self.new_pipeline(new_pipeline_id, root_frame_id, None, window_size, load_data, sandbox, false);
 
-                // Send message to ScriptThread that will suspend all timers
-                match self.pipelines.get(&source_id) {
-                    Some(source) => source.freeze(),
-                    None => warn!("Pipeline {:?} loaded after closure", source_id),
-                };
                 Some(new_pipeline_id)
             }
         }
@@ -2050,13 +2041,9 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             self.focus_pipeline_id = Some(pipeline_id);
         }
 
-        // Suspend the old pipeline, and resume the new one.
+        // Deactivate the old pipeline, and activate the new one.
-        if let Some(pipeline) = self.pipelines.get(&old_pipeline_id) {
+        self.update_activity(old_pipeline_id);
-            pipeline.freeze();
+        self.update_activity(pipeline_id);
-        }
-        if let Some(pipeline) = self.pipelines.get(&pipeline_id) {
-            pipeline.thaw();
-        }
 
         // Set paint permissions correctly for the compositor layers.
         self.send_frame_tree();
@@ -2125,22 +2112,24 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             }
         }
 
-        let (evicted_id, new_frame, clear_future, location_changed) = if let Some(mut entry) = frame_change.replace {
+        let (evicted_id, new_frame, navigated, location_changed) = if let Some(mut entry) = frame_change.replace {
             debug!("Replacing pipeline in existing frame.");
             let evicted_id = entry.pipeline_id;
             entry.replace_pipeline(frame_change.new_pipeline_id, frame_change.url.clone());
             self.traverse_to_entry(entry);
-            (evicted_id, false, false, false)
+            (evicted_id, false, None, false)
         } else if let Some(frame) = self.frames.get_mut(&frame_change.frame_id) {
             debug!("Adding pipeline to existing frame.");
+            let old_pipeline_id = frame.pipeline_id;
             frame.load(frame_change.new_pipeline_id, frame_change.url.clone());
             let evicted_id = frame.prev.len()
                 .checked_sub(PREFS.get("session-history.max-length").as_u64().unwrap_or(20) as usize)
                 .and_then(|index| frame.prev.get_mut(index))
                 .and_then(|entry| entry.pipeline_id.take());
-            (evicted_id, false, true, true)
+            (evicted_id, false, Some(old_pipeline_id), true)
         } else {
-            (None, true, false, true)
+            debug!("Adding pipeline to new frame.");
+            (None, true, None, true)
         };
 
         if let Some(evicted_id) = evicted_id {
@@ -2149,9 +2138,14 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
 
         if new_frame {
             self.new_frame(frame_change.frame_id, frame_change.new_pipeline_id, frame_change.url);
+            self.update_activity(frame_change.new_pipeline_id);
         };
 
-        if clear_future {
+        if let Some(old_pipeline_id) = navigated {
+            // Deactivate the old pipeline, and activate the new one.
+            self.update_activity(old_pipeline_id);
+            self.update_activity(frame_change.new_pipeline_id);
+            // Clear the joint session future
             let top_level_frame_id = self.get_top_level_frame_for_pipeline(frame_change.new_pipeline_id);
             self.clear_joint_session_future(top_level_frame_id);
         }
@@ -2165,7 +2159,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     }
 
     fn handle_activate_document_msg(&mut self, pipeline_id: PipelineId) {
-        debug!("Document ready to activate {:?}", pipeline_id);
+        debug!("Document ready to activate {}", pipeline_id);
 
         // Notify the parent (if there is one).
         if let Some(pipeline) = self.pipelines.get(&pipeline_id) {
@@ -2359,6 +2353,53 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         ReadyToSave::Ready
     }
 
+    /// Get the current activity of a pipeline.
+    fn get_activity(&self, pipeline_id: PipelineId) -> DocumentActivity {
+        let mut ancestor_id = pipeline_id;
+        loop {
+            if let Some(ancestor) = self.pipelines.get(&ancestor_id) {
+                if let Some(frame) = self.frames.get(&ancestor.frame_id) {
+                    if frame.pipeline_id == ancestor_id {
+                        if let Some((parent_id, FrameType::IFrame)) = ancestor.parent_info {
+                            ancestor_id = parent_id;
+                            continue;
+                        } else {
+                            return DocumentActivity::FullyActive;
+                        }
+                    }
+                }
+            }
+            if pipeline_id == ancestor_id {
+                return DocumentActivity::Inactive;
+            } else {
+                return DocumentActivity::Active;
+            }
+        }
+    }
+
+    /// Set the current activity of a pipeline.
+    fn set_activity(&self, pipeline_id: PipelineId, activity: DocumentActivity) {
+        debug!("Setting activity of {} to be {:?}.", pipeline_id, activity);
+        if let Some(pipeline) = self.pipelines.get(&pipeline_id) {
+            pipeline.set_activity(activity);
+            let child_activity = if activity == DocumentActivity::Inactive {
+                DocumentActivity::Active
+            } else {
+                activity
+            };
+            for child_id in &pipeline.children {
+                if let Some(child) = self.frames.get(child_id) {
+                    self.set_activity(child.pipeline_id, child_activity);
+                }
+            }
+        }
+    }
+
+    /// Update the current activity of a pipeline.
+    fn update_activity(&self, pipeline_id: PipelineId) {
+        self.set_activity(pipeline_id, self.get_activity(pipeline_id));
+    }
+
     fn clear_joint_session_future(&mut self, frame_id: FrameId) {
         let frame_ids: Vec<FrameId> = self.full_frame_tree_iter(frame_id)
             .map(|frame| frame.id)

components/constellation/pipeline.rs

@@ -19,7 +19,8 @@ use net_traits::{IpcSend, ResourceThreads};
 use net_traits::image_cache_thread::ImageCacheThread;
 use profile_traits::mem as profile_mem;
 use profile_traits::time;
-use script_traits::{ConstellationControlMsg, DevicePixel, DiscardBrowsingContext, InitialScriptState};
+use script_traits::{ConstellationControlMsg, DevicePixel, DiscardBrowsingContext};
+use script_traits::{DocumentActivity, InitialScriptState};
 use script_traits::{LayoutControlMsg, LayoutMsg, LoadData, MozBrowserEvent};
 use script_traits::{NewLayoutInfo, SWManagerMsg, SWManagerSenders, ScriptMsg};
 use script_traits::{ScriptThreadFactory, TimerEventRequest, WindowSizeData};
@@ -366,17 +367,11 @@ impl Pipeline {
         }
     }
 
-    /// Notify this pipeline that it is no longer fully active.
+    /// Notify this pipeline of its activity.
-    pub fn freeze(&self) {
+    pub fn set_activity(&self, activity: DocumentActivity) {
-        if let Err(e) = self.event_loop.send(ConstellationControlMsg::Freeze(self.id)) {
+        let msg = ConstellationControlMsg::SetDocumentActivity(self.id, activity);
-            warn!("Sending freeze message failed ({}).", e);
+        if let Err(e) = self.event_loop.send(msg) {
-        }
+            warn!("Sending activity message failed ({}).", e);
-    }
-
-    /// Notify this pipeline that it is fully active.
-    pub fn thaw(&self) {
-        if let Err(e) = self.event_loop.send(ConstellationControlMsg::Thaw(self.id)) {
-            warn!("Sending freeze message failed ({}).", e);
         }
     }
 

components/script/dom/bindings/trace.rs

@@ -74,7 +74,7 @@ use profile_traits::time::ProfilerChan as TimeProfilerChan;
 use script_layout_interface::OpaqueStyleAndLayoutData;
 use script_layout_interface::reporter::CSSErrorReporter;
 use script_layout_interface::rpc::LayoutRPC;
-use script_traits::{TimerEventId, TimerSource, TouchpadPressurePhase};
+use script_traits::{DocumentActivity, TimerEventId, TimerSource, TouchpadPressurePhase};
 use script_traits::{UntrustedNodeAddress, WindowSizeData, WindowSizeType};
 use serde::{Deserialize, Serialize};
 use servo_atoms::Atom;
@@ -327,7 +327,7 @@ unsafe_no_jsmanaged_fields!(TrustedPromise);
 unsafe_no_jsmanaged_fields!(PropertyDeclarationBlock);
 // These three are interdependent, if you plan to put jsmanaged data
 // in one of these make sure it is propagated properly to containing structs
-unsafe_no_jsmanaged_fields!(FrameId, FrameType, WindowSizeData, WindowSizeType, PipelineId);
+unsafe_no_jsmanaged_fields!(DocumentActivity, FrameId, FrameType, WindowSizeData, WindowSizeType, PipelineId);
 unsafe_no_jsmanaged_fields!(TimerEventId, TimerSource);
 unsafe_no_jsmanaged_fields!(TimelineMarkerType);
 unsafe_no_jsmanaged_fields!(WorkerId);

components/script/dom/document.rs

@@ -108,7 +108,8 @@ use origin::Origin;
 use script_layout_interface::message::{Msg, ReflowQueryType};
 use script_runtime::{CommonScriptMsg, ScriptThreadEventCategory};
 use script_thread::{MainThreadScriptMsg, Runnable};
-use script_traits::{AnimationState, CompositorEvent, MouseButton, MouseEventType, MozBrowserEvent};
+use script_traits::{AnimationState, CompositorEvent, DocumentActivity};
+use script_traits::{MouseButton, MouseEventType, MozBrowserEvent};
 use script_traits::{ScriptMsg as ConstellationMsg, TouchpadPressurePhase};
 use script_traits::{TouchEventType, TouchId};
 use script_traits::UntrustedNodeAddress;
@@ -191,7 +192,7 @@ pub struct Document {
     last_modified: Option<String>,
     encoding: Cell<EncodingRef>,
     is_html_document: bool,
-    is_fully_active: Cell<bool>,
+    activity: Cell<DocumentActivity>,
     url: DOMRefCell<ServoUrl>,
     quirks_mode: Cell<QuirksMode>,
     /// Caches for the getElement methods
@@ -387,17 +388,33 @@ impl Document {
         self.trigger_mozbrowser_event(MozBrowserEvent::SecurityChange(https_state));
     }
 
-    // https://html.spec.whatwg.org/multipage/#fully-active
     pub fn is_fully_active(&self) -> bool {
-        self.is_fully_active.get()
+        self.activity.get() == DocumentActivity::FullyActive
     }
 
-    pub fn fully_activate(&self) {
+    pub fn is_active(&self) -> bool {
-        self.is_fully_active.set(true)
+        self.activity.get() != DocumentActivity::Inactive
     }
 
-    pub fn fully_deactivate(&self) {
+    pub fn set_activity(&self, activity: DocumentActivity) {
-        self.is_fully_active.set(false)
+        // This function should only be called on documents with a browsing context
+        assert!(self.browsing_context.is_some());
+        // Set the document's activity level, reflow if necessary, and suspend or resume timers.
+        if activity != self.activity.get() {
+            self.activity.set(activity);
+            if activity == DocumentActivity::FullyActive {
+                self.title_changed();
+                self.dirty_all_nodes();
+                self.window().reflow(
+                    ReflowGoal::ForDisplay,
+                    ReflowQueryType::NoQuery,
+                    ReflowReason::CachedPageNeededReflow
+                );
+                self.window().resume();
+            } else {
+                self.window().suspend();
+            }
+        }
     }
 
     pub fn origin(&self) -> &Origin {
@@ -1892,6 +1909,7 @@ impl Document {
                          is_html_document: IsHTMLDocument,
                          content_type: Option<DOMString>,
                          last_modified: Option<String>,
+                         activity: DocumentActivity,
                          source: DocumentSource,
                          doc_loader: DocumentLoader,
                          referrer: Option<String>,
@@ -1927,7 +1945,7 @@ impl Document {
             // https://dom.spec.whatwg.org/#concept-document-encoding
             encoding: Cell::new(UTF_8),
             is_html_document: is_html_document == IsHTMLDocument::HTMLDocument,
-            is_fully_active: Cell::new(false),
+            activity: Cell::new(activity),
             id_map: DOMRefCell::new(HashMap::new()),
             tag_map: DOMRefCell::new(HashMap::new()),
             tagns_map: DOMRefCell::new(HashMap::new()),
@@ -1995,6 +2013,7 @@ impl Document {
                          IsHTMLDocument::NonHTMLDocument,
                          None,
                          None,
+                         DocumentActivity::Inactive,
                          DocumentSource::NotFromParser,
                          docloader,
                          None,
@@ -2008,6 +2027,7 @@ impl Document {
                doctype: IsHTMLDocument,
                content_type: Option<DOMString>,
                last_modified: Option<String>,
+               activity: DocumentActivity,
                source: DocumentSource,
                doc_loader: DocumentLoader,
                referrer: Option<String>,
@@ -2020,6 +2040,7 @@ impl Document {
                                                                       doctype,
                                                                       content_type,
                                                                       last_modified,
+                                                                      activity,
                                                                       source,
                                                                       doc_loader,
                                                                       referrer,
@@ -2093,6 +2114,7 @@ impl Document {
                                         doctype,
                                         None,
                                         None,
+                                        DocumentActivity::Inactive,
                                         DocumentSource::NotFromParser,
                                         DocumentLoader::new(&self.loader()),
                                         None,

components/script/dom/domimplementation.rs

@@ -23,6 +23,7 @@ use dom::htmltitleelement::HTMLTitleElement;
 use dom::node::Node;
 use dom::text::Text;
 use dom::xmldocument::XMLDocument;
+use script_traits::DocumentActivity;
 
 // https://dom.spec.whatwg.org/#domimplementation
 #[dom_struct]
@@ -83,6 +84,7 @@ impl DOMImplementationMethods for DOMImplementation {
                                    IsHTMLDocument::NonHTMLDocument,
                                    Some(DOMString::from(content_type)),
                                    None,
+                                   DocumentActivity::Inactive,
                                    DocumentSource::NotFromParser,
                                    loader);
         // Step 2-3.
@@ -129,6 +131,7 @@ impl DOMImplementationMethods for DOMImplementation {
                                 IsHTMLDocument::HTMLDocument,
                                 None,
                                 None,
+                                DocumentActivity::Inactive,
                                 DocumentSource::NotFromParser,
                                 loader,
                                 None,

components/script/dom/domparser.rs

@@ -19,6 +19,7 @@ use dom::document::{Document, IsHTMLDocument};
 use dom::document::DocumentSource;
 use dom::servoparser::ServoParser;
 use dom::window::Window;
+use script_traits::DocumentActivity;
 
 #[dom_struct]
 pub struct DOMParser {
@@ -65,6 +66,7 @@ impl DOMParserMethods for DOMParser {
                                              IsHTMLDocument::HTMLDocument,
                                              Some(content_type),
                                              None,
+                                             DocumentActivity::Inactive,
                                              DocumentSource::FromParser,
                                              loader,
                                              None,
@@ -82,6 +84,7 @@ impl DOMParserMethods for DOMParser {
                                              IsHTMLDocument::NonHTMLDocument,
                                              Some(content_type),
                                              None,
+                                             DocumentActivity::Inactive,
                                              DocumentSource::NotFromParser,
                                              loader,
                                              None,

components/script/dom/node.rs

@@ -65,6 +65,7 @@ use ref_slice::ref_slice;
 use script_layout_interface::{HTMLCanvasData, OpaqueStyleAndLayoutData, SVGSVGData};
 use script_layout_interface::{LayoutElementType, LayoutNodeType, TrustedNodeAddress};
 use script_layout_interface::message::Msg;
+use script_traits::DocumentActivity;
 use script_traits::UntrustedNodeAddress;
 use selectors::matching::{MatchingReason, matches};
 use selectors::parser::SelectorList;
@@ -1730,7 +1731,8 @@ impl Node {
                                              // https://github.com/whatwg/dom/issues/378
                                              document.origin().alias(),
                                              is_html_doc, None,
-                                             None, DocumentSource::NotFromParser, loader,
+                                             None, DocumentActivity::Inactive,
+                                             DocumentSource::NotFromParser, loader,
                                              None, None);
                 Root::upcast::<Node>(document)
             },

components/script/dom/servoparser/mod.rs

@@ -35,6 +35,7 @@ use network_listener::PreInvoke;
 use profile_traits::time::{TimerMetadata, TimerMetadataFrameType};
 use profile_traits::time::{TimerMetadataReflowType, ProfilerCategory, profile};
 use script_thread::ScriptThread;
+use script_traits::DocumentActivity;
 use servo_config::resource_files::read_resource_file;
 use servo_url::ServoUrl;
 use std::cell::Cell;
@@ -107,6 +108,7 @@ impl ServoParser {
                                      IsHTMLDocument::HTMLDocument,
                                      None,
                                      None,
+                                     DocumentActivity::Inactive,
                                      DocumentSource::FromParser,
                                      loader,
                                      None,

components/script/dom/window.rs

@@ -1488,21 +1488,17 @@ impl Window {
         None
     }
 
-    pub fn freeze(&self) {
+    pub fn suspend(&self) {
         self.upcast::<GlobalScope>().suspend();
         // A hint to the JS runtime that now would be a good time to
         // GC any unreachable objects generated by user script,
         // or unattached DOM nodes. Attached DOM nodes can't be GCd yet,
-        // as the document might be thawed later.
+        // as the document might be reactivated later.
         self.Gc();
     }
 
-    pub fn thaw(&self) {
+    pub fn resume(&self) {
         self.upcast::<GlobalScope>().resume();
-
-        // Push the document title to the compositor since we are
-        // activating this document due to a navigation.
-        self.Document().title_changed();
     }
 
     pub fn need_emit_timeline_marker(&self, timeline_type: TimelineMarkerType) -> bool {

components/script/dom/xmldocument.rs

@@ -17,6 +17,7 @@ use dom::node::Node;
 use dom::window::Window;
 use js::jsapi::{JSContext, JSObject};
 use origin::Origin;
+use script_traits::DocumentActivity;
 use servo_url::ServoUrl;
 
 // https://dom.spec.whatwg.org/#xmldocument
@@ -33,6 +34,7 @@ impl XMLDocument {
                      is_html_document: IsHTMLDocument,
                      content_type: Option<DOMString>,
                      last_modified: Option<String>,
+                     activity: DocumentActivity,
                      source: DocumentSource,
                      doc_loader: DocumentLoader) -> XMLDocument {
         XMLDocument {
@@ -43,6 +45,7 @@ impl XMLDocument {
                                               is_html_document,
                                               content_type,
                                               last_modified,
+                                              activity,
                                               source,
                                               doc_loader,
                                               None,
@@ -57,6 +60,7 @@ impl XMLDocument {
                doctype: IsHTMLDocument,
                content_type: Option<DOMString>,
                last_modified: Option<String>,
+               activity: DocumentActivity,
                source: DocumentSource,
                doc_loader: DocumentLoader)
                -> Root<XMLDocument> {
@@ -68,6 +72,7 @@ impl XMLDocument {
                                            doctype,
                                            content_type,
                                            last_modified,
+                                           activity,
                                            source,
                                            doc_loader),
             window,

components/script/dom/xmlhttprequest.rs

@@ -58,6 +58,7 @@ use net_traits::CoreResourceMsg::Fetch;
 use net_traits::request::{CredentialsMode, Destination, RequestInit, RequestMode};
 use net_traits::trim_http_whitespace;
 use network_listener::{NetworkListener, PreInvoke};
+use script_traits::DocumentActivity;
 use servo_atoms::Atom;
 use servo_config::prefs::PREFS;
 use servo_url::ServoUrl;
@@ -1228,6 +1229,7 @@ impl XMLHttpRequest {
                       is_html_document,
                       content_type,
                       None,
+                      DocumentActivity::Inactive,
                       DocumentSource::FromParser,
                       docloader,
                       None,

components/script/script_thread.rs

@@ -83,7 +83,8 @@ use profile_traits::time::{self, ProfilerCategory, profile};
 use script_layout_interface::message::{self, NewLayoutThreadInfo, ReflowQueryType};
 use script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory, EnqueuedPromiseCallback};
 use script_runtime::{ScriptPort, StackRootTLS, get_reports, new_rt_and_cx, PromiseJobQueue};
-use script_traits::{CompositorEvent, ConstellationControlMsg, DiscardBrowsingContext, EventResult};
+use script_traits::{CompositorEvent, ConstellationControlMsg};
+use script_traits::{DocumentActivity, DiscardBrowsingContext, EventResult};
 use script_traits::{InitialScriptState, LayoutMsg, LoadData, MouseButton, MouseEventType, MozBrowserEvent};
 use script_traits::{NewLayoutInfo, ScriptMsg as ConstellationMsg};
 use script_traits::{ScriptThreadFactory, TimerEvent, TimerEventRequest, TimerSource};
@@ -148,8 +149,8 @@ struct InProgressLoad {
     window_size: Option<WindowSizeData>,
     /// Channel to the layout thread associated with this pipeline.
     layout_chan: Sender<message::Msg>,
-    /// Window is frozen (navigated away while loading for example).
+    /// The activity level of the document (inactive, active or fully active).
-    is_frozen: bool,
+    activity: DocumentActivity,
     /// Window is visible.
     is_visible: bool,
     /// The requested URL of the load.
@@ -172,7 +173,7 @@ impl InProgressLoad {
             parent_info: parent_info,
             layout_chan: layout_chan,
             window_size: window_size,
-            is_frozen: false,
+            activity: DocumentActivity::FullyActive,
             is_visible: true,
             url: url,
             origin: origin,
@@ -963,10 +964,8 @@ impl ScriptThread {
                 self.handle_resize_inactive_msg(id, new_size),
             ConstellationControlMsg::GetTitle(pipeline_id) =>
                 self.handle_get_title_msg(pipeline_id),
-            ConstellationControlMsg::Freeze(pipeline_id) =>
+            ConstellationControlMsg::SetDocumentActivity(pipeline_id, activity) =>
-                self.handle_freeze_msg(pipeline_id),
+                self.handle_set_document_activity_msg(pipeline_id, activity),
-            ConstellationControlMsg::Thaw(pipeline_id) =>
-                self.handle_thaw_msg(pipeline_id),
             ConstellationControlMsg::ChangeFrameVisibilityStatus(pipeline_id, visible) =>
                 self.handle_visibility_change_msg(pipeline_id, visible),
             ConstellationControlMsg::NotifyVisibilityChange(parent_pipeline_id, frame_id, visible) =>
@@ -1303,37 +1302,19 @@ impl ScriptThread {
         warn!("change visibility message sent to nonexistent pipeline");
     }
 
-    /// Handles freeze message
+    /// Handles activity change message
-    fn handle_freeze_msg(&self, id: PipelineId) {
+    fn handle_set_document_activity_msg(&self, id: PipelineId, activity: DocumentActivity) {
         let document = self.documents.borrow().find_document(id);
         if let Some(document) = document {
-            document.window().freeze();
+            document.set_activity(activity);
-            document.fully_deactivate();
             return;
         }
         let mut loads = self.incomplete_loads.borrow_mut();
         if let Some(ref mut load) = loads.iter_mut().find(|load| load.pipeline_id == id) {
-            load.is_frozen = true;
+            load.activity = activity;
             return;
         }
-        warn!("freeze sent to nonexistent pipeline");
+        warn!("change of activity sent to nonexistent pipeline");
-    }
-
-    /// Handles thaw message
-    fn handle_thaw_msg(&self, id: PipelineId) {
-        let document = self.documents.borrow().find_document(id);
-        if let Some(document) = document {
-            self.rebuild_and_force_reflow(&document, ReflowReason::CachedPageNeededReflow);
-            document.window().thaw();
-            document.fully_activate();
-            return;
-        }
-        let mut loads = self.incomplete_loads.borrow_mut();
-        if let Some(ref mut load) = loads.iter_mut().find(|load| load.pipeline_id == id) {
-            load.is_frozen = false;
-            return;
-        }
-        warn!("thaw sent to nonexistent pipeline");
     }
 
     fn handle_focus_iframe_msg(&self,
@@ -1759,16 +1740,13 @@ impl ScriptThread {
                                      is_html_document,
                                      content_type,
                                      last_modified,
+                                     incomplete.activity,
                                      DocumentSource::FromParser,
                                      loader,
                                      referrer,
                                      referrer_policy);
         document.set_ready_state(DocumentReadyState::Loading);
 
-        if !incomplete.is_frozen {
-            document.fully_activate();
-        }
-
         self.documents.borrow_mut().insert(incomplete.pipeline_id, &*document);
 
         window.init_document(&document);
@@ -1822,8 +1800,8 @@ impl ScriptThread {
             ServoParser::parse_html_document(&document, parse_input, final_url);
         }
 
-        if incomplete.is_frozen {
+        if incomplete.activity != DocumentActivity::FullyActive {
-            window.upcast::<GlobalScope>().suspend();
+            window.suspend();
         }
 
         if !incomplete.is_visible {

components/script/timers.rs

@@ -233,6 +233,7 @@ impl OneshotTimers {
             return warn!("Suspending an already suspended timer.");
         }
 
+        debug!("Suspending timers.");
         self.suspended_since.set(Some(precise_time_ms()));
         self.invalidate_expected_event_id();
     }
@@ -244,6 +245,7 @@ impl OneshotTimers {
             None => return warn!("Resuming an already resumed timer."),
         };
 
+        debug!("Resuming timers.");
         self.suspension_offset.set(self.suspension_offset.get() + additional_offset);
         self.suspended_since.set(None);
 
@@ -252,7 +254,7 @@ impl OneshotTimers {
 
     fn schedule_timer_call(&self) {
         if self.suspended_since.get().is_some() {
-            // The timer will be scheduled when the pipeline is thawed.
+            // The timer will be scheduled when the pipeline is fully activated.
             return;
         }
 

components/script_traits/lib.rs

@@ -194,6 +194,22 @@ pub enum DiscardBrowsingContext {
     No,
 }
 
+/// Is a document fully active, active or inactive?
+/// A document is active if it is the current active document in its session history,
+/// it is fuly active if it is active and all of its ancestors are active,
+/// and it is inactive otherwise.
+/// https://html.spec.whatwg.org/multipage/#active-document
+/// https://html.spec.whatwg.org/multipage/#fully-active
+#[derive(Copy, Clone, PartialEq, Eq, Hash, HeapSizeOf, Debug, Deserialize, Serialize)]
+pub enum DocumentActivity {
+    /// An inactive document
+    Inactive,
+    /// An active but not fully active document
+    Active,
+    /// A fully active document
+    FullyActive,
+}
+
 /// Messages sent from the constellation or layout to the script thread.
 #[derive(Deserialize, Serialize)]
 pub enum ConstellationControlMsg {
@@ -215,10 +231,8 @@ pub enum ConstellationControlMsg {
     SetScrollState(PipelineId, Vec<(UntrustedNodeAddress, Point2D<f32>)>),
     /// Requests that the script thread immediately send the constellation the title of a pipeline.
     GetTitle(PipelineId),
-    /// Notifies script thread to suspend all its timers
+    /// Notifies script thread of a change to one of its document's activity
-    Freeze(PipelineId),
+    SetDocumentActivity(PipelineId, DocumentActivity),
-    /// Notifies script thread to resume all its timers
-    Thaw(PipelineId),
     /// Notifies script thread whether frame is visible
     ChangeFrameVisibilityStatus(PipelineId, bool),
     /// Notifies script thread that frame visibility change is complete
@@ -281,8 +295,7 @@ impl fmt::Debug for ConstellationControlMsg {
             Viewport(..) => "Viewport",
             SetScrollState(..) => "SetScrollState",
             GetTitle(..) => "GetTitle",
-            Freeze(..) => "Freeze",
+            SetDocumentActivity(..) => "SetDocumentActivity",
-            Thaw(..) => "Thaw",
             ChangeFrameVisibilityStatus(..) => "ChangeFrameVisibilityStatus",
             NotifyVisibilityChange(..) => "NotifyVisibilityChange",
             Navigate(..) => "Navigate",