ui: Revert gfx::BufferUsage::SCANOUT to gfx::BufferUsage::GPU_READ_WRITE change.

ui/ozone/demo/surfaceless_gl_renderer.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/ozone/demo/surfaceless_gl_renderer.h"
 
 #include "base/bind.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
@@ skipping 22 matching lines @@
 bool SurfacelessGlRenderer::BufferWrapper::Initialize(
     gfx::AcceleratedWidget widget,
     const gfx::Size& size) {
   glGenFramebuffersEXT(1, &gl_fb_);
   glGenTextures(1, &gl_tex_);
 
   scoped_refptr<NativePixmap> pixmap =
       OzonePlatform::GetInstance()
           ->GetSurfaceFactoryOzone()
           ->CreateNativePixmap(widget, size, gfx::BufferFormat::BGRX_8888,
-                               gfx::BufferUsage::GPU_READ_WRITE);
+                               gfx::BufferUsage::SCANOUT);
   scoped_refptr<gfx::GLImageOzoneNativePixmap> image(
       new gfx::GLImageOzoneNativePixmap(size, GL_RGB));
   if (!image->Initialize(pixmap.get(), gfx::BufferFormat::BGRX_8888)) {
     LOG(ERROR) << "Failed to create GLImage";
     return false;
   }
   image_ = image;
 
   glBindFramebufferEXT(GL_FRAMEBUFFER, gl_fb_);
   glBindTexture(GL_TEXTURE_2D, gl_tex_);
@@ skipping 77 matching lines @@
     case gfx::SwapResult::SWAP_ACK:
       GlRenderer::PostRenderFrameTask(result);
       break;
     case gfx::SwapResult::SWAP_FAILED:
       LOG(FATAL) << "Failed to swap buffers";
       break;
   }
 }
 
 }  // namespace ui