ozone: scenic: Scale entity so that texture size can be fixed at 1x1

This will allow the GPU process to avoid worrying about the display scale
when setting up its Scenic resources.

Bug: 861853
Test: run_content_shell --ozone-platform=scenic --disable-gpu --enable-vulkan

Change-Id: I19571bd55ccbc004c42230ec7aba98dcd5370d11
Reviewed-on: https://chromium-review.googlesource.com/c/1342815Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609431}

ui/ozone/platform/scenic/scenic_window.cc

@@ -191,14 +191,16 @@ void ScenicWindow::UpdateSize() {
     screen->OnWindowBoundsChanged(window_id_, size_rect);
 
   // Set node shape to rectangle that matches size of the view.
-  scenic::Rectangle rect(&scenic_session_, size_dips_.width(),
-                         size_dips_.height());
+  scenic::Rectangle rect(&scenic_session_, 1.f, 1.f);
   shape_node_.SetShape(rect);
 
   // Translate the node by half of the view dimensions to put it in the center
   // of the view.
-  shape_node_.SetTranslation(size_dips_.width() / 2.0,
-                             size_dips_.height() / 2.0, 0.f);
+  node_.SetTranslation(size_dips_.width() / 2.0, size_dips_.height() / 2.0,
+                       0.f);
+
+  // Scale the node so that surface rect can always be 1x1.
+  node_.SetScale(size_dips_.width(), size_dips_.height(), 1.f);
 
   // This is necessary when using vulkan because ImagePipes are presented
   // separately and we need to make sure our sizes change is committed.