@CalledByNative
 private void didDeferAfterResponseStarted(
     String markup, String cssSelector, String enteringColor) {
   if (mNavigationTransitionDelegate != null) {
     mNavigationTransitionDelegate.didDeferAfterResponseStarted(
         markup, cssSelector, enteringColor);
   }
 }
 @CalledByNative
 private void didStartNavigationTransitionForFrame(long frameId) {
   if (mNavigationTransitionDelegate != null) {
     mNavigationTransitionDelegate.didStartNavigationTransitionForFrame(frameId);
   }
 }
 @CalledByNative
 private void addEnteringStylesheetToTransition(String stylesheet) {
   if (mNavigationTransitionDelegate != null) {
     mNavigationTransitionDelegate.addEnteringStylesheetToTransition(stylesheet);
   }
 }
 @CalledByNative
 private boolean willHandleDeferAfterResponseStarted() {
   if (mNavigationTransitionDelegate == null) return false;
   return mNavigationTransitionDelegate.willHandleDeferAfterResponseStarted();
 }