Don't fake surface sizes on Mac.

This was causing window resize jank. This hack was added in r364897, and
it's unclear to me if it's needed on Mac. Removing it seems to work, but
I wish I had more context.

Bug: 682825
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: I1d9e1224297d78f3c5a08a6774acbe816a6e1c81
Reviewed-on: https://chromium-review.googlesource.com/1069037Reviewed-by: ccameron <ccameron@chromium.org>
Commit-Queue: Sidney San Martín <sdy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560859}

components/viz/host/renderer_settings_creation.cc

@@ -49,6 +49,7 @@ RendererSettings CreateRendererSettings() {
   renderer_settings.finish_rendering_on_resize = true;
 #elif defined(OS_MACOSX)
   renderer_settings.release_overlay_resources_after_gpu_query = true;
+  renderer_settings.auto_resize_output_surface = false;
 #endif
   renderer_settings.tint_gl_composited_content =
       command_line->HasSwitch(switches::kTintGlCompositedContent);