Android: Force draw for pending readbacks during Display teardown

content/browser/renderer_host/compositor_impl_android.cc

 // 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.
 
 #include "content/browser/renderer_host/compositor_impl_android.h"
 
 #include <android/bitmap.h>
 #include <android/native_window_jni.h>
 #include <stdint.h>
 #include <unordered_set>
@@ skipping 386 matching lines @@
       output_surface_request_pending_(false),
       needs_begin_frames_(false),
       weak_factory_(this) {
   ui::ContextProviderFactory::GetInstance()
       ->GetSurfaceManager()
       ->RegisterSurfaceClientId(surface_id_allocator_->client_id());
   DCHECK(client);
   DCHECK(root_window);
   DCHECK(root_window->GetLayer() == nullptr);
   root_window->SetLayer(cc::Layer::Create());
+  readback_layer_tree_ = cc::Layer::Create();
+  readback_layer_tree_->SetHideLayerAndSubtree(true);
+  root_window->GetLayer()->AddChild(readback_layer_tree_);
   root_window->AttachCompositor(this);
   CreateLayerTreeHost();
   resource_manager_.Init(host_.get());
 }
 
 CompositorImpl::~CompositorImpl() {
   root_window_->DetachCompositor();
   root_window_->SetLayer(nullptr);
   // Clean-up any surface references.
   SetSurface(NULL);
@@ skipping 90 matching lines @@
   host_->SetDeviceScaleFactor(device_scale_factor_);
 
   if (needs_animate_)
     host_->SetNeedsAnimate();
 }
 
 void CompositorImpl::SetVisible(bool visible) {
   TRACE_EVENT1("cc", "CompositorImpl::SetVisible", "visible", visible);
   if (!visible) {
     DCHECK(host_->visible());
+
+    // Make a best effort to try to complete pending readbacks.
+    // TODO(crbug.com/637035): Consider doing this in a better way,
+    // ideally with the guarantee of readbacks completing.
+    if (display_.get() && HavePendingReadbacks())
+      display_->ForceImmediateDrawAndSwapIfPossible();
+
     host_->SetVisible(false);
     if (!host_->output_surface_lost())
       host_->ReleaseOutputSurface();
     pending_swapbuffers_ = 0;
     display_.reset();
   } else {
     host_->SetVisible(true);
     if (output_surface_request_pending_)
       HandlePendingOutputSurfaceRequest();
   }
@@ skipping 217 matching lines @@
   if (host_->visible())
     host_->SetNeedsCommit();
   client_->OnSwapBuffersCompleted(0);
 }
 
 void CompositorImpl::DidCommit() {
   root_window_->OnCompositingDidCommit();
 }
 
 void CompositorImpl::AttachLayerForReadback(scoped_refptr<cc::Layer> layer) {
-  root_window_->GetLayer()->AddChild(layer);
+  readback_layer_tree_->AddChild(layer);
 }
 
 void CompositorImpl::RequestCopyOfOutputOnRootLayer(
     std::unique_ptr<cc::CopyOutputRequest> request) {
   root_window_->GetLayer()->RequestCopyOfOutput(std::move(request));
 }
 
 void CompositorImpl::OnVSync(base::TimeTicks frame_time,
                              base::TimeDelta vsync_period) {
   FOR_EACH_OBSERVER(VSyncObserver, observer_list_,
@@ skipping 13 matching lines @@
 
 void CompositorImpl::SetNeedsAnimate() {
   needs_animate_ = true;
   if (!host_->visible())
     return;
 
   TRACE_EVENT0("compositor", "Compositor::SetNeedsAnimate");
   host_->SetNeedsAnimate();
 }
 
+bool CompositorImpl::HavePendingReadbacks() {
+  return !readback_layer_tree_->children().empty();
+}
+
 }  // namespace content