ozone: Reject overlays when a test buffer can't be allocated.

ui/ozone/platform/drm/gpu/drm_overlay_validator.cc

 // Copyright 2015 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/platform/drm/gpu/drm_overlay_validator.h"
 
 #include <drm_fourcc.h>
 
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/ozone/platform/drm/common/drm_util.h"
@@ skipping 114 matching lines @@
 
   for (auto& overlay : validated_params) {
     if (!overlay.is_overlay_candidate)
       continue;
 
     gfx::Size scaled_buffer_size = GetScaledSize(
         overlay.buffer_size, overlay.display_rect, overlay.crop_rect);
 
     uint32_t original_format = GetFourCCFormatForFramebuffer(overlay.format);
     scoped_refptr<ScanoutBuffer> buffer =
-        GetBufferForPageFlipTest(drm, scaled_buffer_size, original_format,
+        GetBufferForPageFlipTest(drm, overlay.buffer_size, original_format,
                                  buffer_generator_, &reusable_buffers);
-    DCHECK(buffer);
 
     OverlayPlane plane(buffer, overlay.plane_z_order, overlay.transform,
                        overlay.display_rect, overlay.crop_rect);
     test_list.push_back(plane);
 
-    if (controller->TestPageFlip(test_list)) {
+    if (buffer && controller->TestPageFlip(test_list)) {
       overlay.is_overlay_candidate = true;
 
       // If size scaling is needed, find an optimal format.
       if (overlay.plane_z_order && scaled_buffer_size != overlay.buffer_size) {
         uint32_t optimal_format = FindOptimalBufferFormat(
             original_format, overlay.plane_z_order, overlay.display_rect,
             window_->bounds(), controller);
 
         if (original_format != optimal_format) {
           OverlayPlane original_plain = test_list.back();
@@ skipping 108 matching lines @@
 
     // Make sure we dont hold reference to buffer when caching this plane list.
     plane.buffer = nullptr;
   }
 
   DCHECK(hints_plane_list.size() == overlay_hints.size());
   overlay_hints_cache_.Put(hints_plane_list, overlay_hints);
 }
 
 }  // namespace ui