Ensure fullscreen mode is exited for same-site navigations.

content/browser/frame_host/navigator_delegate.h

Index: content/browser/frame_host/navigator_delegate.h
diff --git a/content/browser/frame_host/navigator_delegate.h b/content/browser/frame_host/navigator_delegate.h
index ab70aac7fe6cf560554c9d2a154535cc17d53036..e92dbeee495bf9beb5b4529ccedc8866d569dc46 100644
--- a/content/browser/frame_host/navigator_delegate.h
+++ b/content/browser/frame_host/navigator_delegate.h
@@ -59,6 +59,11 @@ class CONTENT_EXPORT NavigatorDelegate {
       const GURL& url,
       PageTransition transition_type) {}
 
+  // Handles post-navigation tasks in navigation BEFORE the entry has been
+  // committed to the NavigationController.
+  virtual void DidNavigateMainFramePreCommit(
+      const FrameHostMsg_DidCommitProvisionalLoad_Params& params) {}
+
   // Handles post-navigation tasks in navigation AFTER the entry has been
   // committed to the NavigationController. Note that the NavigationEntry is
   // not provided since it may be invalid/changed after being committed. The