DL: rendersubtree attribute

Add the rendersubtree attribute (and renderSubtree property), accepting
the values "visible", "invisible", "invisible-activatable".

Will lock/unlock accordingly when the attribute is added/removed/changed
its value. Activation will set the attribute to "visible".

Note:
- acquire(), commit(), updateAndCommit() won't set/remove/change the
attribute at all. These functions (and Element.displayLock) will be
removed in another CL.
- Containment is not implied by this attribute and no DevTools error
for containment-related failures yet. Those will be
added in another CL.
- content-sizing is not currently supported. content-size CSS property
will be implemented in another CL.

See discussion:
WICG/display-locking#62 (comment)

Bug: 991095
Change-Id: I81ef6e6ff8bb5718dfb8ee09de701a08ed92062f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1735579
Reviewed-by: Chris Harrelson OOO <chrishtr@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685940}

third_party/blink/renderer/core/display_lock/display_lock_context.cc

@@ -154,19 +154,13 @@ ScriptPromise DisplayLockContext::acquire(ScriptState* script_state,
                           ? options->timeout()
                           : kDefaultLockTimeoutMs;
 
-  if (IsLocked()) {
-    // If we're locked, the activatable flag might change the activation
-    // blocking lock count. If we're not locked, the activation blocking lock
-    // count will be updated when we changed the state.
-    state_.UpdateActivationBlockingCount(activatable_,
-                                         options && options->activatable());
-  }
-  activatable_ = options && options->activatable();
+  // We always reschedule a timeout task even if we're not starting a new
+  // acquire. The reason for this is that the last acquire dictates the timeout
+  // interval. Note that the following call cancels any existing timeout tasks.
+  RescheduleTimeoutTask(timeout_ms);
 
-  // If we're acquiring something that isn't currently locked, we need to recalc
-  // the layout size. Otherwise if we're re-acquiring, we only need to recalc if
-  // the locked size has changed.
-  bool should_recalc_layout_size = !IsLocked();
+  // We need to recalc if the locked size has changed.
+  bool should_recalc_layout_size = false;
   if (options && options->hasSize()) {
     auto parsed_size = ParseAndVerifySize(options->size());
     if (!parsed_size)
@@ -181,11 +175,6 @@ ScriptPromise DisplayLockContext::acquire(ScriptState* script_state,
     locked_content_logical_size_ = LayoutSize();
   }
 
-  // We always reschedule a timeout task even if we're not starting a new
-  // acquire. The reason for this is that the last acquire dictates the timeout
-  // interval. Note that the following call cancels any existing timeout tasks.
-  RescheduleTimeoutTask(timeout_ms);
-
   if (should_recalc_layout_size && ConnectedToView()) {
     if (auto* layout_object = element_->GetLayoutObject()) {
       layout_object->SetNeedsLayoutAndPrefWidthsRecalc(
@@ -194,6 +183,8 @@ ScriptPromise DisplayLockContext::acquire(ScriptState* script_state,
     ScheduleAnimation();
   }
 
+  SetActivatable(options && options->activatable());
+
   if (acquire_resolver_)
     return acquire_resolver_->Promise();
 
@@ -209,39 +200,60 @@ ScriptPromise DisplayLockContext::acquire(ScriptState* script_state,
   // property is false).
   FinishCommitResolver(kResolve);
 
+  StartAcquire();
+
+  // If we're not connected, resolve immediately.
+  if (!ConnectedToView())
+    return GetResolvedPromise(script_state);
+
+  MakeResolver(script_state, &acquire_resolver_);
+  return acquire_resolver_->Promise();
+}
+
+void DisplayLockContext::SetActivatable(bool activatable) {
+  if (IsLocked()) {
+    // If we're locked, the activatable flag might change the activation
+    // blocking lock count. If we're not locked, the activation blocking lock
+    // count will be updated when we changed the state.
+    state_.UpdateActivationBlockingCount(activatable_, activatable);
+  }
+  activatable_ = activatable;
+}
+
+void DisplayLockContext::StartAcquire() {
+  DCHECK(!IsLocked());
   update_budget_.reset();
   state_ = kLocked;
 
   // If we're already connected then we need to ensure that we update our style
   // to check for containment later, layout size based on the options, and
   // also clear the painted output.
-  if (ConnectedToView()) {
-    element_->SetNeedsStyleRecalc(
-        kLocalStyleChange,
-        StyleChangeReasonForTracing::Create(style_change_reason::kDisplayLock));
-    MakeResolver(script_state, &acquire_resolver_);
+  if (!ConnectedToView())
+    return;
+
+  element_->SetNeedsStyleRecalc(
+      kLocalStyleChange,
+      StyleChangeReasonForTracing::Create(style_change_reason::kDisplayLock));
+  ScheduleAnimation();
+
+  auto* layout_object = element_->GetLayoutObject();
+  if (!layout_object) {
     is_horizontal_writing_mode_ = true;
-    if (auto* layout_object = element_->GetLayoutObject()) {
-      is_horizontal_writing_mode_ = layout_object->IsHorizontalWritingMode();
-      // GraphicsLayer collection would normally skip layers if paint is blocked
-      // by display-locking (see: CollectDrawableLayersForLayerListRecursively
-      // in LocalFrameView). However, if we don't trigger this collection, then
-      // we might use the cached result instead. In order to ensure we skip the
-      // newly locked layers, we need to set |need_graphics_layer_collection_|
-      // before marking the layer for repaint.
-      needs_graphics_layer_collection_ = true;
-      MarkPaintLayerNeedsRepaint();
-    }
-    // TODO(vmpstr): This needs to be set after invalidation above, since we
-    // want the object to layout once. After the changes to separate self and
-    // child layout, this would no longer be required and we can set the
-    // container as locked earlier.
-    state_ = kLocked;
-    return acquire_resolver_->Promise();
+    return;
   }
 
-  // Otherwise (if we're not connected), resolve immediately.
-  return GetResolvedPromise(script_state);
+  layout_object->SetNeedsLayoutAndPrefWidthsRecalc(
+      layout_invalidation_reason::kDisplayLock);
+
+  is_horizontal_writing_mode_ = layout_object->IsHorizontalWritingMode();
+  // GraphicsLayer collection would normally skip layers if paint is blocked
+  // by display-locking (see: CollectDrawableLayersForLayerListRecursively
+  // in LocalFrameView). However, if we don't trigger this collection, then
+  // we might use the cached result instead. In order to ensure we skip the
+  // newly locked layers, we need to set |need_graphics_layer_collection_|
+  // before marking the layer for repaint.
+  needs_graphics_layer_collection_ = true;
+  MarkPaintLayerNeedsRepaint();
 }
 
 ScriptPromise DisplayLockContext::update(ScriptState* script_state) {
@@ -517,6 +529,10 @@ void DisplayLockContext::CommitForActivation() {
   DCHECK(ConnectedToView());
   DCHECK(ShouldCommitForActivation());
   StartCommit();
+  // Since setting the attribute might trigger a commit if we are still locked,
+  // we set it after we start the commit.
+  if (element_->hasAttribute(html_names::kRendersubtreeAttr))
+    element_->setAttribute(html_names::kRendersubtreeAttr, "visible");
 }
 
 bool DisplayLockContext::ShouldCommitForActivation() const {
@@ -555,6 +571,7 @@ void DisplayLockContext::NotifyForcedUpdateScopeEnded() {
 }
 
 void DisplayLockContext::StartCommit() {
+  DCHECK(IsLocked());
   // Since we are starting a commit, cancel the timeout task.
   CancelTimeoutTask();
   if (CleanupAndRejectCommitIfNotConnected())

third_party/blink/renderer/core/display_lock/display_lock_context.h

@@ -103,6 +103,13 @@ class CORE_EXPORT DisplayLockContext final
   ScriptPromise commit(ScriptState*);
   ScriptPromise updateAndCommit(ScriptState*);
 
+  void SetActivatable(bool activatable);
+
+  // Acquire the lock, should only be called when unlocked.
+  void StartAcquire();
+  // Initiate a commit.
+  void StartCommit();
+
   enum LifecycleTarget { kSelf, kChildren };
 
   // Lifecycle observation / state functions.
@@ -217,8 +224,6 @@ class CORE_EXPORT DisplayLockContext final
     UntracedMember<DisplayLockContext> context_;
   };
 
-  // Initiate a commit.
-  void StartCommit();
   // Initiate an update.
   void StartUpdateIfNeeded();
 

third_party/blink/renderer/core/dom/element.cc

@@ -1927,6 +1927,24 @@ void Element::AttributeChanged(const AttributeModificationParams& params) {
                name == html_names::kInvisibleAttr &&
                params.old_value != params.new_value) {
       InvisibleAttributeChanged(params.old_value, params.new_value);
+    } else if (RuntimeEnabledFeatures::DisplayLockingEnabled() &&
+               name == html_names::kRendersubtreeAttr &&
+               params.old_value != params.new_value) {
+      const bool should_be_invisible =
+          EqualIgnoringASCIICase(params.new_value, "invisible");
+      const bool should_be_invisible_activatable =
+          EqualIgnoringASCIICase(params.new_value, "invisible-activatable");
+      if (should_be_invisible || should_be_invisible_activatable) {
+        // Getting locked.
+        EnsureDisplayLockContext().SetActivatable(
+            should_be_invisible_activatable);
+        if (!GetDisplayLockContext()->IsLocked())
+          GetDisplayLockContext()->StartAcquire();
+      } else {
+        // Getting unlocked.
+        if (EnsureDisplayLockContext().IsLocked())
+          GetDisplayLockContext()->StartCommit();
+      }
     }
   }
 
@@ -4129,6 +4147,11 @@ DisplayLockContext* Element::GetDisplayLockContext() const {
                        : nullptr;
 }
 
+DisplayLockContext& Element::EnsureDisplayLockContext() {
+  return *EnsureElementRareData().EnsureDisplayLockContext(
+      this, GetExecutionContext());
+}
+
 // Step 1 of http://domparsing.spec.whatwg.org/#insertadjacenthtml()
 static Element* ContextElementForInsertion(const String& where,
                                            Element* element,

third_party/blink/renderer/core/dom/element.h

@@ -911,6 +911,7 @@ class CORE_EXPORT Element : public ContainerNode, public Animatable {
 
   DisplayLockContext* getDisplayLockForBindings();
   DisplayLockContext* GetDisplayLockContext() const;
+  DisplayLockContext& EnsureDisplayLockContext();
 
   bool StyleRecalcBlockedByDisplayLock(
       DisplayLockContext::LifecycleTarget) const;

third_party/blink/renderer/core/dom/element.idl

@@ -144,6 +144,8 @@ callback ScrollStateCallback = void (ScrollState scrollState);
 
     // Display locking. Returns a display lock context.
     [RuntimeEnabled=DisplayLocking, ImplementedAs=getDisplayLockForBindings] readonly attribute DisplayLockContext displayLock;
+    // Declarative display locking.
+    [RuntimeEnabled=DisplayLocking, CEReactions, CustomElementCallbacks, Reflect, ReflectOnly=("invisible-activatable","invisible", "visible"), ReflectInvalid="visible", ReflectEmpty="visible"] attribute DOMString renderSubtree;
 
     // Element Timing
     [RuntimeEnabled=ElementTiming, Affects=Nothing, CEReactions, Reflect=elementtiming] attribute DOMString elementTiming;

third_party/blink/renderer/core/html/html_attribute_names.json5

@@ -274,6 +274,7 @@
     "preload",
     "pseudo",
     "readonly",
+    "rendersubtree",
     "referrerpolicy",
     "rel",
     "required",

third_party/blink/web_tests/TestExpectations

@@ -258,11 +258,12 @@ crbug.com/882663 inspector-protocol/css [ Skip ]
 
 # Display locking failures
 crbug.com/955533 wpt_internal/display-lock/sizing/overflow-auto-with-overflow.html [ Failure ]
+# Skip some tests for rendersubtree
+crbug.com/991095 wpt_internal/display-lock/rendersubtree/containment [ Skip ]
+crbug.com/991095 wpt_internal/display-lock/rendersubtree/sizing [ Skip ]
 
 # virtual-scroller failures
 crbug.com/986574 wpt_internal/virtual-scroller/ [ Failure ]
-# Skip tests for rendersubtree for now.
-crbug.com/991095 wpt_internal/display-lock/rendersubtree/ [ Skip ]
 
 # Sheriff 2018/05/25
 crbug.com/846747 http/tests/navigation/navigation-interrupted-by-fragment.html  [ Pass Timeout ]

third_party/blink/web_tests/webexposed/element-instance-property-listing-expected.txt

@@ -278,6 +278,7 @@ namespace http://www.w3.org/1999/xhtml
     property removeAttributeNode
     property removeChild
     property removeEventListener
+    property renderSubtree
     property replaceChild
     property replaceWith
     property requestFullscreen
@@ -1454,6 +1455,7 @@ namespace http://www.w3.org/2000/svg
     property removeAttributeNode
     property removeChild
     property removeEventListener
+    property renderSubtree
     property replaceChild
     property replaceWith
     property requestFullscreen

third_party/blink/web_tests/webexposed/global-interface-listing-expected.txt

@@ -2019,6 +2019,7 @@ interface Element : Node
     getter part
     getter prefix
     getter previousElementSibling
+    getter renderSubtree
     getter role
     getter scrollHeight
     getter scrollLeft
@@ -2141,6 +2142,7 @@ interface Element : Node
     setter onwebkitfullscreenerror
     setter outerHTML
     setter part
+    setter renderSubtree
     setter role
     setter scrollLeft
     setter scrollTop

third_party/blink/web_tests/wpt_internal/display-lock/rendersubtree/acquire-commit.html

@@ -6,6 +6,7 @@
 <link rel="help" href="https://github.com/WICG/display-locking">
 <link rel="match" href="pass-container-with-child-ref.html">
 <script src="/common/reftest-wait.js"></script>
+<script src="resources/utils.js"></script>
 
 <style>
 #container {
@@ -33,12 +34,12 @@
 
 function runTest() {
   const container = document.getElementById("container");
-  container.displayLock.acquire({ timeout: Infinity }).then(() => {
+  setInvisible(container).then(() => {
     const child = document.createElement("div");
     child.id = "child";
     container.appendChild(child);
 
-    container.displayLock.commit().then(
+    setVisible(container).then(
       () => { finishTest("PASS"); },
       (e) => { finishTest("FAIL " + e.message); });
   });

third_party/blink/web_tests/wpt_internal/display-lock/rendersubtree/acquire-immediate-commit-resolves.html

@@ -6,6 +6,7 @@
 <link rel="help" href="https://github.com/WICG/display-locking">
 <link rel="match" href="pass-container-with-child-ref.html">
 <script src="/common/reftest-wait.js"></script>
+<script src="resources/utils.js"></script>
 
 <style>
 #container {
@@ -33,13 +34,13 @@
 
 function runTest() {
   const container = document.getElementById("container");
-  container.displayLock.acquire({ timeout: Infinity });
+  setInvisible(container);
 
   const child = document.createElement("div");
   child.id = "child";
   container.appendChild(child);
 
-  container.displayLock.commit().then(
+  setVisible(container).then(
     () => { finishTest("PASS"); },
     (e) => { finishTest("FAIL " + e.message); });
 }

third_party/blink/web_tests/wpt_internal/display-lock/rendersubtree/acquire-immediate-update-and-commit.html

@@ -6,6 +6,7 @@
 <link rel="help" href="https://github.com/WICG/display-locking">
 <link rel="match" href="pass-container-with-child-ref.html">
 <script src="/common/reftest-wait.js"></script>
+<script src="resources/utils.js"></script>
 
 <style>
 #container {
@@ -33,7 +34,7 @@
 
 function runTest() {
   const container = document.getElementById("container");
-  container.displayLock.acquire({ timeout: Infinity });
+  setInvisible(container);
 
   const child = document.createElement("div");
   child.id = "child";

third_party/blink/web_tests/wpt_internal/display-lock/rendersubtree/acquire-in-breakable-div.html

@@ -6,6 +6,7 @@
 <link rel="help" href="https://github.com/WICG/display-locking">
 <link rel="match" href="acquire-in-breakable-div-ref.html">
 <script src="/common/reftest-wait.js"></script>
+<script src="resources/utils.js"></script>
 
 <style>
 #container {
@@ -28,7 +29,7 @@
 <script>
 async function runTest() {
   const container = document.getElementById("container");
-  await container.displayLock.acquire({ timeout: Infinity });
+  await setInvisible(container);
   takeScreenshot();
 }
 

third_party/blink/web_tests/wpt_internal/display-lock/rendersubtree/acquire-in-iframe.html

@@ -6,6 +6,7 @@
 <link rel="help" href="https://github.com/WICG/display-locking">
 <link rel="match" href="acquire-in-iframe-ref.html">
 <script src="/common/reftest-wait.js"></script>
+<script src="resources/utils.js"></script>
 
 <div id="log"></div>
 <iframe id="frame" srcdoc='
@@ -28,7 +29,7 @@
 
 function runTest() {
   const container = document.getElementById("frame").contentDocument.getElementById("container");
-  container.displayLock.acquire({ timeout: Infinity }).then(
+  setInvisible(container).then(
     () => { finishTest("PASS"); },
     (e) => { finishTest("FAIL " + e.message); });
 }

third_party/blink/web_tests/wpt_internal/display-lock/rendersubtree/acquire-on-composited-layer.html

@@ -6,6 +6,7 @@
 <link rel="help" href="https://github.com/WICG/display-locking">
 <link rel="match" href="pass-ref.html">
 <script src="/common/reftest-wait.js"></script>
+<script src="resources/utils.js"></script>
 
 <style>
 #container {
@@ -28,7 +29,7 @@
 
 function runTest() {
   const container = document.getElementById("container");
-  container.displayLock.acquire({ timeout: Infinity }).then(
+  setInvisible(container).then(
     () => { finishTest("PASS"); },
     (e) => { finishTest("FAIL " + e.message); }
   );