Fix mouse wheel over-scrolls when display is scaled and scroll is paginated

third_party/WebKit/public/web/WebViewClient.h

Index: third_party/WebKit/public/web/WebViewClient.h
diff --git a/third_party/WebKit/public/web/WebViewClient.h b/third_party/WebKit/public/web/WebViewClient.h
index af3fe7c18514915fa668e2101eac7a937cc7fbe9..9040e13f840be5cfca316bc21cd4714c8dcbba09 100644
--- a/third_party/WebKit/public/web/WebViewClient.h
+++ b/third_party/WebKit/public/web/WebViewClient.h
@@ -271,6 +271,7 @@ class WebViewClient : protected WebWidgetClient {
                      const WebFloatSize& accumulatedOverscroll,
                      const WebFloatPoint& positionInViewport,
                      const WebFloatSize& velocityInViewport) override {}
+  float GetOriginalDeviceScaleFactor() const override { return 1.0f; }

[chengx, 2017/01/06 23:46:36]

Bret:
Be careful adding functions to the public interfaces. I don't think Blink should
have access to the device scale factor directly.

   void hasTouchEventHandlers(bool) override {}
   void initializeLayerTreeView() override {}
   void resetInputMethod() override {}