ozone: demo: Remove duplicate render frame in surfaceless mode

Since the surfaceless renderers inherit the surface renderers, we
actually initially post two tasks to render frame. This results in
tearing.

Remove the duplicate post. As a followup, this inheritance should
be removed since it is too error prone.

Bug: 836971
Test: ozone_demo on eve
Change-Id: If79edf65f6aba2cc239f0e349860d6b56ba82450
Reviewed-on: https://chromium-review.googlesource.com/1028844Reviewed-by: Albert Chaulk <achaulk@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553782}

ui/ozone/demo/skia/skia_surfaceless_gl_renderer.cc

@@ -189,7 +189,6 @@ bool SurfacelessSkiaGlRenderer::Initialize() {
   }
 
   disable_primary_plane_ = command_line->HasSwitch(kDisablePrimaryPlane);
-  PostRenderFrameTask(gfx::SwapResult::SWAP_ACK);
   return true;
 }
 

ui/ozone/demo/surfaceless_gl_renderer.cc

@@ -157,7 +157,6 @@ bool SurfacelessGlRenderer::Initialize() {
   }
 
   disable_primary_plane_ = command_line->HasSwitch("disable-primary-plane");
-  PostRenderFrameTask(gfx::SwapResult::SWAP_ACK);
   return true;
 }