content: Add overdraw feedback support for X11 ChromeOS builds.

content/browser/compositor/gpu_browser_compositor_output_surface.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 "content/browser/compositor/gpu_browser_compositor_output_surface.h"
 
 #include <utility>
 
 #include "build/build_config.h"
 #include "cc/output/output_surface_client.h"
 #include "cc/output/output_surface_frame.h"
 #include "components/display_compositor/compositor_overlay_candidate_validator.h"
 #include "content/browser/compositor/reflector_impl.h"
 #include "content/browser/compositor/reflector_texture.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "gpu/command_buffer/client/context_support.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/ipc/client/command_buffer_proxy_impl.h"
 #include "services/ui/public/cpp/gpu/context_provider_command_buffer.h"
 
 namespace content {
 
 GpuBrowserCompositorOutputSurface::GpuBrowserCompositorOutputSurface(
     scoped_refptr<ui::ContextProviderCommandBuffer> context,
     const UpdateVSyncParametersCallback& update_vsync_parameters_callback,
     std::unique_ptr<display_compositor::CompositorOverlayCandidateValidator>
-        overlay_candidate_validator)
+        overlay_candidate_validator,
+    bool support_stencil)
     : BrowserCompositorOutputSurface(std::move(context),
                                      update_vsync_parameters_callback,
                                      std::move(overlay_candidate_validator)),
       weak_ptr_factory_(this) {
   if (capabilities_.uses_default_gl_framebuffer) {
     capabilities_.flipped_output_surface =
         context_provider()->ContextCapabilities().flips_vertically;
   }
+  capabilities_.supports_stencil = support_stencil;

[jbauman, 2017/01/19 01:53:59]

We should really try to grab this from the context, as there's no guarantee it's
supported even if we ask for it.

[reveman, 2017/01/19 04:15:08]

I think what we really want to do is prefer an X visual with stencil bits and
only mark this as supported if one was found. That is if we're on X11 (only case
today when this will be true and we're not surfaceless). It happens that the
preferred visual on X always has stencil support and I considered adding some
code here to check that but it seemed overkill for this debugging feature. Added
a TODO here to latest patch that we can follow up on if needed.

 }
 
 GpuBrowserCompositorOutputSurface::~GpuBrowserCompositorOutputSurface() {
   GetCommandBufferProxy()->SetUpdateVSyncParametersCallback(
       UpdateVSyncParametersCallback());
 }
 
 void GpuBrowserCompositorOutputSurface::OnGpuSwapBuffersCompleted(
     const std::vector<ui::LatencyInfo>& latency_info,
     gfx::SwapResult result,
@@ skipping 92 matching lines @@
 GpuBrowserCompositorOutputSurface::GetCommandBufferProxy() {
   ui::ContextProviderCommandBuffer* provider_command_buffer =
       static_cast<ui::ContextProviderCommandBuffer*>(context_provider_.get());
   gpu::CommandBufferProxyImpl* command_buffer_proxy =
       provider_command_buffer->GetCommandBufferProxy();
   DCHECK(command_buffer_proxy);
   return command_buffer_proxy;
 }
 
 }  // namespace content