gpu: Empty swaps for surfaceless output surfaces.

services/ui/surfaces/display_output_surface_ozone.cc

 // Copyright 2016 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 "services/ui/surfaces/display_output_surface_ozone.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
@@ skipping 65 matching lines @@
 }
 
 void DisplayOutputSurfaceOzone::SwapBuffers(cc::OutputSurfaceFrame frame) {
   DCHECK(buffer_queue_);
 
   // TODO(rjkroege): What if swap happens again before DidReceiveSwapBuffersAck
   // then it would see the wrong size?
   DCHECK(reshape_size_ == frame.size);
   swap_size_ = reshape_size_;
 
-  buffer_queue_->SwapBuffers(frame.sub_buffer_rect ? *frame.sub_buffer_rect
-                                                   : gfx::Rect(swap_size_));
+  gfx::Rect damage_rect =
+      frame.sub_buffer_rect ? *frame.sub_buffer_rect : gfx::Rect(swap_size_);
+  // Use previous buffer when damage rect is empty. This avoids unnecessary
+  // partial swap work and makes it possible to support empty swaps on devices
+  // where partial swaps are disabled.
+  if (!damage_rect.IsEmpty())
+    buffer_queue_->SwapBuffers(damage_rect);
+
   DisplayOutputSurface::SwapBuffers(std::move(frame));
 }
 
 uint32_t DisplayOutputSurfaceOzone::GetFramebufferCopyTextureFormat() {
   return buffer_queue_->internal_format();
 }
 
 bool DisplayOutputSurfaceOzone::IsDisplayedAsOverlayPlane() const {
   // TODO(rjkroege): implement remaining overlay functionality.
   return true;
 }
 
 unsigned DisplayOutputSurfaceOzone::GetOverlayTextureId() const {
-  return buffer_queue_->current_texture_id();
+  return buffer_queue_->GetCurrentTextureId();
 }
 
 void DisplayOutputSurfaceOzone::DidReceiveSwapBuffersAck(
     gfx::SwapResult result) {
   bool force_swap = false;
   if (result == gfx::SwapResult::SWAP_NAK_RECREATE_BUFFERS) {
     // Even through the swap failed, this is a fixable error so we can pretend
     // it succeeded to the rest of the system.
     result = gfx::SwapResult::SWAP_ACK;
     buffer_queue_->RecreateBuffers();
     force_swap = true;
   }
 
   buffer_queue_->PageFlipComplete();
   client()->DidReceiveSwapBuffersAck();
 
   if (force_swap)
     client()->SetNeedsRedrawRect(gfx::Rect(swap_size_));
 }
 
 }  // namespace ui