Move Document.fullscreenElement to DocumentOrShadowRoot

third_party/WebKit/Source/core/dom/Fullscreen.cpp

Index: third_party/WebKit/Source/core/dom/Fullscreen.cpp
diff --git a/third_party/WebKit/Source/core/dom/Fullscreen.cpp b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
index f30793ebf893232c84067a756b252a75473c91a3..1fc1a22d476a98d86066752028cbe2bb69a1b918 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.cpp
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
@@ -212,12 +212,42 @@ Element* Fullscreen::fullscreenElementFrom(Document& document) {
   return nullptr;
 }
 
+Element* Fullscreen::fullscreenElementForBindingFrom(TreeScope& scope) {
+  Element* element = fullscreenElementFrom(scope.document());
+  if (!element || !RuntimeEnabledFeatures::fullscreenUnprefixedEnabled())
+    return element;
+
+  // TODO(kochi): Once V0 code is removed, we can use the same logic for
+  // Document and ShadowRoot.
+  if (!scope.rootNode().isShadowRoot()) {
+    // For Shadow DOM V0 compatibility: We allow returning an element in V0

[foolip, 2016/10/24 15:30:12]

Do you want to attempt all of these changes at once? If it's fine to do them
one-by-one, then just not having this code and tying the behavior change to
unprefixed Fullscreen seems OK. If not, why not the same logic for
Fullscreen::currentFullScreenElementForBindingFrom below?

[kochi, 2016/10/25 10:08:04]

Ah good catch! I forgot to add this logic to
Fullscreen::currentFullScreenElementForBindingFrom below.
(the layout test case didn't catch this unfortunately, as
document.adjustedElement() does also skip V0 shadow root.)

+    // shadow tree, even though it leaks the Shadow DOM.
+    if (element->isInV0ShadowTree()) {
+      UseCounter::count(scope.document(),
+                        UseCounter::DocumentFullscreenElementInV0Shadow);
+      return element;
+    }
+  } else {
+    if (!toShadowRoot(scope).isV1())
+      return nullptr;
+  }
+  return scope.adjustedElement(*element);
+}
+
 Element* Fullscreen::currentFullScreenElementFrom(Document& document) {
   if (Fullscreen* found = fromIfExists(document))
     return found->currentFullScreenElement();
   return nullptr;
 }
 
+Element* Fullscreen::currentFullScreenElementForBindingFrom(
+    Document& document) {
+  Element* element = currentFullScreenElementFrom(document);
+  if (!element || !RuntimeEnabledFeatures::fullscreenUnprefixedEnabled())
+    return element;
+  return document.adjustedElement(*element);
+}
+
 Fullscreen::Fullscreen(Document& document)
     : ContextLifecycleObserver(&document),
       m_fullScreenLayoutObject(nullptr),