Add support for entering/exiting HTML fullscreen from OOPIFs.

third_party/WebKit/Source/web/FullscreenController.h

Index: third_party/WebKit/Source/web/FullscreenController.h
diff --git a/third_party/WebKit/Source/web/FullscreenController.h b/third_party/WebKit/Source/web/FullscreenController.h
index b321ce83a71a4475d1fd5fdb116af6865d8ea9b7..3f68e6dd74e9fa0d0121a90ccaa851ff715e2c18 100644
--- a/third_party/WebKit/Source/web/FullscreenController.h
+++ b/third_party/WebKit/Source/web/FullscreenController.h
@@ -56,6 +56,8 @@ public:
 
     bool isFullscreen() { return m_fullScreenFrame; }
 
+    void setFullscreenIsForCrossProcessAncestor() { m_fullscreenIsForCrossProcessAncestor = true; }
+
     void updateSize();
 
     DECLARE_TRACE();
@@ -79,6 +81,10 @@ private:
     // If set, the WebView is in fullscreen mode for an element in this frame.
     Member<LocalFrame> m_fullScreenFrame;
 
+    // If set, fullscreen is entered for an element that is a container for
+    // another fullscreen element in an out-of-process iframe.
+    bool m_fullscreenIsForCrossProcessAncestor;
+
     bool m_isCancelingFullScreen;
 };