Add support for entering/exiting HTML fullscreen from OOPIFs.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index e44ae4fe13c652d497333368835aabb7ef3d62f9..d49111a7c3cf46346454da22d8d35649ec03d748 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1866,11 +1866,9 @@ void WebContentsImpl::ExitFullscreenMode(bool will_cause_resize) {
                         will_cause_resize));
 }
 
+// TODO(alexmos): Remove the unused |render_widget_host| parameter.
 bool WebContentsImpl::IsFullscreenForCurrentTab(
     RenderWidgetHostImpl* render_widget_host) const {
-  if (!RenderViewHostImpl::From(render_widget_host))
-    return false;
-
   return delegate_ ? delegate_->IsFullscreenForTabOrPending(this) : false;
 }