Add test for paint underinvalidation fix with animated transform overflow.

third_party/WebKit/Source/web/tests/sim/SimCompositor.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "web/tests/sim/SimCompositor.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/layout/compositing/CompositedLayerMapping.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
@@ skipping 61 matching lines @@
 }
 
 void SimCompositor::registerSelection(const WebSelection&) {
   m_hasSelection = true;
 }
 
 void SimCompositor::clearSelection() {
   m_hasSelection = false;
 }
 
-SimDisplayItemList SimCompositor::beginFrame() {
+SimDisplayItemList SimCompositor::beginFrame(double dt) {
   DCHECK(m_webViewImpl);
   DCHECK(!m_deferCommits);
   DCHECK(m_needsBeginFrame);
   m_needsBeginFrame = false;
 
-  // Always advance the time as if the compositor was running at 60fps.
-  m_lastFrameTimeMonotonic = monotonicallyIncreasingTime() + 0.016;
+  m_lastFrameTimeMonotonic = monotonicallyIncreasingTime() + dt;
 
   m_webViewImpl->beginFrame(m_lastFrameTimeMonotonic);
   m_webViewImpl->updateAllLifecyclePhases();
 
   LocalFrame* root = m_webViewImpl->mainFrameImpl()->frame();
 
   SimDisplayItemList displayList;
   paintFrames(*root, displayList);
 
   return displayList;
 }
 
 }  // namespace blink