Avoid rotation anchor during transitional fullscreen states.

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1901 matching lines @@
 
   FrameView* view = mainFrame->frameView();
   if (!view)
     return;
 
   VisualViewport& visualViewport = page()->frameHost().visualViewport();
 
   bool isRotation =
       page()->settings().getMainFrameResizesAreOrientationChanges() &&
       m_size.width && contentsSize().width() && newSize.width != m_size.width &&
-      !m_fullscreenController->isFullscreen();
+      !m_fullscreenController->isFullscreenOrTransitioning();
   m_size = newSize;
 
   FloatSize viewportAnchorCoords(viewportAnchorCoordX, viewportAnchorCoordY);
   if (isRotation) {
     RotationViewportAnchor anchor(*view, visualViewport, viewportAnchorCoords,
                                   pageScaleConstraintsSet());
     resizeViewWhileAnchored(browserControlsHeight, browserControlsShrinkLayout);
   } else {
     ResizeViewportAnchor::ResizeScope resizeScope(*m_resizeViewportAnchor);
     resizeViewWhileAnchored(browserControlsHeight, browserControlsShrinkLayout);
@@ skipping 2233 matching lines @@
   if (focusedFrame->localFrameRoot() != mainFrameImpl()->frame())
     return nullptr;
   return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const {
   return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink