Compute the popup location/size correctly 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 d9881f67aa15a37d90b1b9a6f17b58552791a1b8..d5d67e4eb9c6dcc89e7f6889b743224314884410 100644
--- a/components/test_runner/web_test_delegate.h
+++ b/components/test_runner/web_test_delegate.h
@@ -161,6 +161,9 @@ class WebTestDelegate {
   // Controls the device scale factor of the main WebView for hidpi tests.
   virtual void SetDeviceScaleFactor(float factor) = 0;
 
+  // Enable zoom-for-dsf option.
+  virtual void EnableUseZoomForDSF() = 0;
+
   // Change the device color profile while running a layout test.
   virtual void SetDeviceColorProfile(const std::string& name) = 0;