Move test away from sniffing UpdateVisualProperties IPC.

The last sent VisualProperties is available as a member on RWHI, add
an accessor and adjust the test to use that. We need move this message
to mojo and is is easier to read the last sent value than adding a
mojo interceptor.

BUG=1097816

Change-Id: I3c27a452f3fcbafdec80c092abd9a2b6e65e1d33
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2302449
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789616}

content/browser/renderer_host/render_widget_host_impl.cc

@@ -2899,6 +2899,13 @@ RenderWidgetHostImpl::GetFrameWidgetInputHandler() {
   return frame_widget_input_handler_.get();
 }
 
+base::Optional<blink::VisualProperties>
+RenderWidgetHostImpl::GetLastVisualPropertiesSentToRendererForTesting() {
+  if (!old_visual_properties_)
+    return base::nullopt;
+  return *old_visual_properties_;
+}
+
 void RenderWidgetHostImpl::DispatchInputEventWithLatencyInfo(
     const blink::WebInputEvent& event,
     ui::LatencyInfo* latency) {

content/browser/renderer_host/render_widget_host_impl.h

@@ -802,6 +802,10 @@ class CONTENT_EXPORT RenderWidgetHostImpl
     return blink_widget_host_receiver_;
   }
 
+  // Returns the visual properties that were last sent to the renderer.
+  base::Optional<blink::VisualProperties>
+  GetLastVisualPropertiesSentToRendererForTesting();
+
  protected:
   // ---------------------------------------------------------------------------
   // The following method is overridden by RenderViewHost to send upwards to