Android: Force draw for pending readbacks during Display teardown

content/browser/renderer_host/compositor_impl_android.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_COMPOSITOR_IMPL_ANDROID_H_
 #define CONTENT_BROWSER_RENDERER_HOST_COMPOSITOR_IMPL_ANDROID_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 115 matching lines @@
 #if defined(ENABLE_VULKAN)
   void CreateVulkanOutputSurface();
 #endif
   void CreateCompositorOutputSurface(
       const scoped_refptr<cc::ContextProvider>& context_provider);
   void InitializeDisplay(
       std::unique_ptr<cc::OutputSurface> display_output_surface,
       scoped_refptr<cc::VulkanContextProvider> vulkan_context_provider,
       scoped_refptr<cc::ContextProvider> context_provider);
 
+  bool HavePendingReadbacks();
+
   // root_layer_ is the persistent internal root layer, while subroot_layer_
   // is the one attached by the compositor client.
   scoped_refptr<cc::Layer> subroot_layer_;
 
+  // Subtree for hidden layers with CopyOutputRequests on them.
+  scoped_refptr<cc::Layer> readback_layer_tree_;
+
   // Destruction order matters here:
   std::unique_ptr<cc::SurfaceIdAllocator> surface_id_allocator_;
   base::ObserverList<VSyncObserver, true> observer_list_;
   std::unique_ptr<cc::LayerTreeHost> host_;
   ui::ResourceManagerImpl resource_manager_;
 
   std::unique_ptr<cc::Display> display_;
 
   gfx::Size size_;
   bool has_transparent_background_;
@@ skipping 24 matching lines @@
   gpu::Capabilities gpu_capabilities_;
   bool needs_begin_frames_;
   base::WeakPtrFactory<CompositorImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositorImpl);
 };
 
 } // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_COMPOSITOR_IMPL_ANDROID_H_