Fix OOPIF hit testing in layout tests.

If we haven't received an activated surface yet ensure that we fallback
to querying the renderer for the target of input events.

BUG=601584

Change-Id: Id5dfcdb6bf54b98bebbd2a3b715d77202f402781
Reviewed-on: https://chromium-review.googlesource.com/1131219Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573789}

content/browser/renderer_host/render_widget_host_view_base.cc

@@ -518,6 +518,8 @@ viz::FrameSinkId RenderWidgetHostViewBase::FrameSinkIdAtPoint(
       gfx::ConvertPointToPixel(device_scale_factor, point);
   viz::SurfaceId surface_id = GetCurrentSurfaceId();
   if (!surface_id.is_valid()) {
+    // Force a query of the renderer if we don't have a surface id yet.
+    *out_query_renderer = true;
     return GetFrameSinkId();
   }
   viz::SurfaceHittest hittest(delegate,