[CompositeAfterPaint] Ensure animation timeline is attached to host

We need to attach the document animation timeline to the animation host
to make animations work. In pre-CompositeAfterPaint, this is done from
PaintLayerCompositor.

For CompositeAfterPaint, attach animation timeline from
Document::Initialize() and WebLocalFrameImpl::SetFrameWidget().

Bug: 702353
Change-Id: I5e19add5196e5b52ebcade42b58e336051b111e6
Reviewed-on: https://chromium-review.googlesource.com/c/1368994Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615554}

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

@@ -2725,6 +2725,9 @@ void Document::Initialize() {
   // attached to a frame. Otherwise ContextLifecycleObserver::contextDestroyed
   // wouldn't be fired.
   network_state_observer_ = MakeGarbageCollected<NetworkStateObserver>(*this);
+
+  if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled())
+    AttachCompositorAnimationTimeline();
 }
 
 void Document::Shutdown() {
@@ -2772,8 +2775,16 @@ void Document::Shutdown() {
 
   markers_->PrepareForDestruction();
 
-  if (GetPage())
+  if (GetPage()) {
     GetPage()->DocumentDetached(this);
+    if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled()) {
+      if (auto* compositor_timeline = Timeline().CompositorTimeline()) {
+        GetPage()->GetChromeClient().DetachCompositorAnimationTimeline(
+            compositor_timeline, frame_.Get());
+      }
+    }
+  }
+
   probe::documentDetached(this);
 
   // FIXME: consider using PausableObject.
@@ -7174,6 +7185,14 @@ Locale& Document::GetCachedLocale(const AtomicString& locale) {
   return *(result.stored_value->value);
 }
 
+void Document::AttachCompositorAnimationTimeline() {
+  DCHECK(RuntimeEnabledFeatures::CompositeAfterPaintEnabled());
+  if (auto* compositor_timeline = Timeline().CompositorTimeline()) {
+    GetPage()->GetChromeClient().AttachCompositorAnimationTimeline(
+        compositor_timeline, frame_.Get());
+  }
+}
+
 AnimationClock& Document::GetAnimationClock() {
   DCHECK(GetPage());
   return GetPage()->Animator().Clock();

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

@@ -1237,6 +1237,11 @@ class CORE_EXPORT Document : public ContainerNode,
   // Return a Locale for the default locale if the argument is null or empty.
   Locale& GetCachedLocale(const AtomicString& locale = g_null_atom);
 
+  // For CompositeAfterPaint. This is called internally from Initialize(), but
+  // for the local frame root, the frame widget may be not set at the time,
+  // so this is also called from WebLocalFrameImpl::SetFrameWidget().
+  void AttachCompositorAnimationTimeline();
+
   AnimationClock& GetAnimationClock();
   DocumentTimeline& Timeline() const { return *timeline_; }
   PendingAnimations& GetPendingAnimations() { return *pending_animations_; }

third_party/blink/renderer/core/frame/web_local_frame_impl.cc

@@ -2327,6 +2327,14 @@ void WebLocalFrameImpl::WillDetachParent() {
 
 void WebLocalFrameImpl::SetFrameWidget(WebFrameWidgetBase* frame_widget) {
   frame_widget_ = frame_widget;
+
+  // This is needed because the local frame root's widget may not be set when
+  // Document::Initialize() called AttachmentCompositorAnimationTimeline()
+  // (which requires frame widget to be effective).
+  if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled() && frame_widget) {
+    if (auto* document = GetFrame()->GetDocument())
+      document->AttachCompositorAnimationTimeline();
+  }
 }
 
 WebFrameWidget* WebLocalFrameImpl::FrameWidget() const {

third_party/blink/renderer/core/page/chrome_client_impl.cc

@@ -734,9 +734,10 @@ void ChromeClientImpl::AttachCompositorAnimationTimeline(
     CompositorAnimationTimeline* compositor_timeline,
     LocalFrame* local_frame) {
   WebLocalFrameImpl* web_frame = WebLocalFrameImpl::FromFrame(local_frame);
-  if (CompositorAnimationHost* animation_host =
-          web_frame->LocalRootFrameWidget()->AnimationHost())
-    animation_host->AddTimeline(*compositor_timeline);
+  if (auto* widget = web_frame->LocalRootFrameWidget()) {
+    if (auto* animation_host = widget->AnimationHost())
+      animation_host->AddTimeline(*compositor_timeline);
+  }
 }
 
 void ChromeClientImpl::DetachCompositorAnimationTimeline(

third_party/blink/web_tests/FlagExpectations/enable-blink-features=CompositeAfterPaint

@@ -367,10 +367,6 @@ crbug.com/589265 fast/forms/text/input-appearance-autocomplete-very-long-value.h
 crbug.com/589265 animations/svg/animated-filter-svg-element.html [ Failure ]
 crbug.com/589265 virtual/threaded/animations/svg/animated-filter-svg-element.html [ Failure ]
 
-# Some work remains to fully support composited animation and scrolling.
-crbug.com/702350 virtual/threaded/transitions/opacity-transform-transitions-inside-iframe.html [ Timeout ]
-crbug.com/702353 virtual/threaded/transitions/transition-end-event-destroy-iframe.html [ Timeout ]
-
 # virtual/threaded variants of sub-directories and tests already skipped or marked as failing above.
 Bug(none) virtual/threaded/http/tests/devtools/ [ Skip ]
 Bug(none) virtual/threaded/fast/events/pinch/gesture-pinch-zoom-scroll-bubble.html [ Failure Crash ]