Partial swap implementation for surfaceless

content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc

Index: content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
diff --git a/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc b/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
index a1e7f54a117e103294fa4a0217e1d53a4983b881..198712bd4bf27b5bc4e5dc0aa64445fe449bf660 100644
--- a/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
+++ b/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
@@ -38,6 +38,8 @@ void GpuSurfacelessBrowserCompositorOutputSurface::SwapBuffers(
     cc::CompositorFrame* frame) {
   DCHECK(output_surface_);
 
+  output_surface_->SwapBuffers(frame->gl_frame_data->sub_buffer_rect);
+
   const gfx::Size& size = frame->gl_frame_data->size;
   context_provider_->ContextGL()->ScheduleOverlayPlaneCHROMIUM(
       0,
@@ -51,7 +53,6 @@ void GpuSurfacelessBrowserCompositorOutputSurface::SwapBuffers(
       0,
       1.0f,
       1.0f);
-  output_surface_->SwapBuffers();
   GpuBrowserCompositorOutputSurface::SwapBuffers(frame);
 }