gui: make PixelWidget pass keypresses through so they reach scrollbars

Change-Id: Icf1604b01d50f33fd2209ce858c3e978d6064472
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/apitrace/+/2224549
Reviewed-by: Po-Hsien Wang <pwang@chromium.org>
Commit-Queue: Robert Tarasov <tutankhamen@chromium.org>
Tested-by: Robert Tarasov <tutankhamen@chromium.org>
diff --git a/gui/pixelwidget.cpp b/gui/pixelwidget.cpp
index 8f8fdc7..5a25c8e 100644
--- a/gui/pixelwidget.cpp
+++ b/gui/pixelwidget.cpp
@@ -207,6 +207,9 @@
     case Qt::Key_Control:
         grabKeyboard();
         break;
+    default:
+        QWidget::keyPressEvent(e);
+        break;
     }
 }