Reland: Add support for entering/exiting HTML fullscreen from OOPIFs.

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

Index: third_party/WebKit/Source/core/dom/Fullscreen.h
diff --git a/third_party/WebKit/Source/core/dom/Fullscreen.h b/third_party/WebKit/Source/core/dom/Fullscreen.h
index 8c1d0eda503eecd9664a109aae72aa2e2b14f60a..9761c4fea2205bd6afc79f296517ba7a32934f89 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.h
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.h
@@ -74,8 +74,14 @@ public:
     static bool fullscreenEnabled(Document&);
     Element* fullscreenElement() const { return !m_fullScreenElementStack.isEmpty() ? m_fullScreenElementStack.last().first.get() : 0; }
 
-    void didEnterFullScreenForElement(Element*);
-    void didExitFullScreenForElement(Element*);
+    // |isAncestorOfFullscreenElement| is used in OOPIF scenarios and is set to
+    // true when these functions are called to enter/exit fullscreen for an
+    // out-of-process descendant element.  In this case, we enter fullscreen
+    // for its (local) iframe container and make sure to also set the
+    // ContainsFullScreenElement flag on it (so that it gains the
+    // -webkit-full-screen-ancestor style).
+    void didEnterFullScreenForElement(Element*, bool isAncestorOfFullscreenElement);
+    void didExitFullScreenForElement(bool isAncestorOfFullscreenElement);
 
     void setFullScreenLayoutObject(LayoutFullScreen*);
     LayoutFullScreen* fullScreenLayoutObject() const { return m_fullScreenLayoutObject; }