Don't restart the ImageQualityController timer unless it is already half over.

third_party/WebKit/Source/web/WebViewImpl.h

 /*
  * Copyright (C) 2010 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 507 matching lines @@
     // Detaches the PaintArtifactCompositor and clears the layer tree view's
     // root layer.
     void detachPaintArtifactCompositor();
 
     // Use in Slimming Paint v2 to update the layer tree for the content.
     PaintArtifactCompositor& getPaintArtifactCompositor() { return m_paintArtifactCompositor; }
 
     bool isTransparent() const;
     void setIsTransparent(bool value);
 
+    double lastFrameTimeMonotonic() const { return m_lastFrameTimeMonotonic; }
+
 private:
     InspectorOverlay* inspectorOverlay();
 
     void setPageScaleFactorAndLocation(float, const FloatPoint&);
 
     void scrollAndRescaleViewports(float scaleFactor, const IntPoint& mainFrameOrigin, const FloatPoint& visualViewportOrigin);
 
     float maximumLegiblePageScale() const;
     void refreshPageScaleFactorAfterLayout();
     void resumeTreeViewCommitsIfRenderingReady();
@@ skipping 206 matching lines @@
     FloatSize m_elasticOverscroll;
 
     Persistent<EventListener> m_popupMouseWheelEventListener;
 
     WebPageImportanceSignals m_pageImportanceSignals;
 
     const OwnPtr<WebViewScheduler> m_scheduler;
 
     // Manages the layer tree created for this page in Slimming Paint v2.
     PaintArtifactCompositor m_paintArtifactCompositor;
+
+    double m_lastFrameTimeMonotonic;
 };
 
 DEFINE_TYPE_CASTS(WebViewImpl, WebWidget, widget, widget->isWebView(), widget.isWebView());
 // We have no ways to check if the specified WebView is an instance of
 // WebViewImpl because WebViewImpl is the only implementation of WebView.
 DEFINE_TYPE_CASTS(WebViewImpl, WebView, webView, true, true);
 
 } // namespace blink
 
 #endif