input: Change how synthesized events are dispatched in telemetry tests.

content/test/test_render_view_host.h

Index: content/test/test_render_view_host.h
diff --git a/content/test/test_render_view_host.h b/content/test/test_render_view_host.h
index 9bbee7414f7423d21581dbee832ec0eddc195e40..9f01ac1c64c259a12823f8a7fbad49cd1ac884a3 100644
--- a/content/test/test_render_view_host.h
+++ b/content/test/test_render_view_host.h
@@ -103,6 +103,7 @@ class TestRenderWidgetHostView : public RenderWidgetHostViewBase {
   void Focus() override {}
   void SetIsLoading(bool is_loading) override {}
   void UpdateCursor(const WebCursor& cursor) override {}
+  void OnSetNeedsFlushInput() override {}
   void RenderProcessGone(base::TerminationStatus status,
                          int error_code) override;
   void Destroy() override;