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

third_party/WebKit/Source/web/WebViewImpl.h

Index: third_party/WebKit/Source/web/WebViewImpl.h
diff --git a/third_party/WebKit/Source/web/WebViewImpl.h b/third_party/WebKit/Source/web/WebViewImpl.h
index 0338de5c6af28012ed375bd606b8d9049d1cb352..f63cf13e2e135a825d98a2f12414fedbba6420ce 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.h
+++ b/third_party/WebKit/Source/web/WebViewImpl.h
@@ -525,6 +525,8 @@ public:
     bool isTransparent() const;
     void setIsTransparent(bool value);
 
+    double lastFrameTimeMonotonic() const { return m_lastFrameTimeMonotonic; }
+
 private:
     InspectorOverlay* inspectorOverlay();
 
@@ -751,6 +753,8 @@ private:
 
     // 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());