Add test for paint underinvalidation fix with animated transform overflow.

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

 // 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.
 
 #ifndef SimCompositor_h
 #define SimCompositor_h
 
 #include "public/platform/WebLayerTreeView.h"
 
 namespace blink {
@@ skipping 12 matching lines @@
 // Note: This also does not support compositor driven animations.
 class SimCompositor final : public WebLayerTreeView {
  public:
   explicit SimCompositor();
   ~SimCompositor();
 
   void setWebViewImpl(WebViewImpl&);
 
   // Execute the BeginMainFrame processing steps, an approximation of what
   // cc::ThreadProxy::BeginMainFrame would do.
-  SimDisplayItemList beginFrame();
+  SimDisplayItemList beginFrame(double dt = 0.016);
 
   bool needsBeginFrame() const { return m_needsBeginFrame; }
   bool deferCommits() const { return m_deferCommits; }
 
   bool hasSelection() const { return m_hasSelection; }
 
  private:
   void setNeedsBeginFrame() override;
   void setNeedsCompositorUpdate() override;
   void setDeferCommits(bool) override;
   void registerSelection(const WebSelection&) override;
   void clearSelection() override;
 
   bool m_needsBeginFrame;
   bool m_deferCommits;
   bool m_hasSelection;
   WebViewImpl* m_webViewImpl;
   double m_lastFrameTimeMonotonic;
 };
 
 }  // namespace blink
 
 #endif