Add support for entering/exiting HTML fullscreen from OOPIFs.

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 e2398d48e5034f604f927bf9099f59b68da460dd..58440dd00e87283f85c142f17de4adbca84da24e 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.cpp
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
@@ -410,7 +410,7 @@ bool Fullscreen::fullscreenEnabled(Document& document)
     return fullscreenIsAllowedForAllOwners(document) && fullscreenIsSupported(document);
 }
 
-void Fullscreen::didEnterFullScreenForElement(Element* element)
+void Fullscreen::didEnterFullScreenForElement(Element* element, bool isAncestorOfFullscreenElement)
 {
     DCHECK(element);
     if (!document()->isActive())
@@ -432,10 +432,20 @@ void Fullscreen::didEnterFullScreenForElement(Element* element)
         m_savedPlaceholderComputedStyle = ComputedStyle::clone(layoutObject->styleRef());
     }
 
+    // TODO(alexmos): When |isAncestorOfFullscreenElement| is true, some of
+    // this layout work has already been done in another process, so it should
+    // not be necessary to repeat it here.
     if (m_fullScreenElement != document()->documentElement())
         LayoutFullScreen::wrapLayoutObject(layoutObject, layoutObject ? layoutObject->parent() : 0, document());
 
+    if (isAncestorOfFullscreenElement) {
+        DCHECK(m_fullScreenElement->isFrameOwnerElement());
+        DCHECK(toHTMLFrameOwnerElement(m_fullScreenElement)->contentFrame()->isRemoteFrame());
+        m_fullScreenElement->setContainsFullScreenElement(true);
+    }
+
     m_fullScreenElement->setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(true);
+
     document()->styleEngine().ensureFullscreenUAStyle();
     m_fullScreenElement->pseudoStateChanged(CSSSelector::PseudoFullScreen);
 
@@ -450,7 +460,7 @@ void Fullscreen::didEnterFullScreenForElement(Element* element)
     m_eventQueueTimer.startOneShot(0, BLINK_FROM_HERE);
 }
 
-void Fullscreen::didExitFullScreenForElement(Element*)
+void Fullscreen::didExitFullScreenForElement(bool isAncestorOfFullscreenElement)

[dcheng, 2016/05/18 01:04:34]

See below comment. Wondering if we need this parameter at all: can it be
inferred by the fact that m_fullScreenElement is an HTMLFrameOwnerElement with a
RemoteFrame for its content frame?

[alexmos, 2016/05/18 15:08:33]

I actually started out with that approach, but turns out it can't distinguish
between fullscreening the actual HTMLIFrameElement (with a RemoteFrame) in the
parent frame and fullscreening some element in the child frame.  In  the parent
process, both will end up setting the same element as m_fullScreenElement, but
they need to behave slightly differently: the latter needs the
:-webkit-full-screen-ancestor CSS but the former doesn't (hence the check
below).

 {
     if (!m_fullScreenElement)
         return;
@@ -460,6 +470,9 @@ void Fullscreen::didExitFullScreenForElement(Element*)
 
     m_fullScreenElement->willStopBeingFullscreenElement();
 
+    if (isAncestorOfFullscreenElement)
+        m_fullScreenElement->setContainsFullScreenElement(false);
+
     m_fullScreenElement->setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(false);
 
     if (m_fullScreenLayoutObject)