Scale the emulated event in EventSender when use-zoom-for-dsf is enabled

components/test_runner/web_test_delegate.h

Index: components/test_runner/web_test_delegate.h
diff --git a/components/test_runner/web_test_delegate.h b/components/test_runner/web_test_delegate.h
index 1c2af2d4fab74dd1ab2eaf4dab3e7ce87ce470d9..80e9675b3377cd05b6f545f2f26ecbd85e34b771 100644
--- a/components/test_runner/web_test_delegate.h
+++ b/components/test_runner/web_test_delegate.h
@@ -158,6 +158,11 @@ class WebTestDelegate {
   // Controls the device scale factor of the main WebView for hidpi tests.
   virtual void SetDeviceScaleFactor(float factor) = 0;
 
+  // When use-zoom-for-dsf mode is enabled, this returns the scale to
+  // convert from window coordinates to viewport coordinates. When
+  // use-zoom-for-dsf is disabled, this return always 1.0f.
+  virtual float GetWindowToViewportScale() = 0;
+
   // Enable zoom-for-dsf option.
   virtual void EnableUseZoomForDSF() = 0;