cc: Make LayerTreeHostImpl::SwapBuffers not virtual.

cc/test/fake_output_surface.cc

Index: cc/test/fake_output_surface.cc
diff --git a/cc/test/fake_output_surface.cc b/cc/test/fake_output_surface.cc
index 876b64f986309ce228bebf681327b8655d28fee3..65ec1af0e04be6b404740182897551fd5181257e 100644
--- a/cc/test/fake_output_surface.cc
+++ b/cc/test/fake_output_surface.cc
@@ -42,9 +42,11 @@ FakeOutputSurface::FakeOutputSurface(
   capabilities_.delegated_rendering = delegated_rendering;
 }
 
-FakeOutputSurface::~FakeOutputSurface() {}
+FakeOutputSurface::~FakeOutputSurface() = default;
 
 void FakeOutputSurface::SwapBuffers(CompositorFrame frame) {
+  ReturnResourcesHeldByParent();
+
   std::unique_ptr<CompositorFrame> frame_copy(new CompositorFrame);
   *frame_copy = std::move(frame);
   if (frame_copy->delegated_frame_data || !context_provider()) {
@@ -95,25 +97,17 @@ bool FakeOutputSurface::BindToClient(OutputSurfaceClient* client) {
   }
 }
 
+void FakeOutputSurface::DetachFromClient() {
+  ReturnResourcesHeldByParent();
+  OutputSurface::DetachFromClient();
+}
+
 void FakeOutputSurface::SetTreeActivationCallback(
     const base::Closure& callback) {
   DCHECK(client_);
   client_->SetTreeActivationCallback(callback);
 }
 
-void FakeOutputSurface::ReturnResource(unsigned id, CompositorFrameAck* ack) {
-  TransferableResourceArray::iterator it;
-  for (it = resources_held_by_parent_.begin();
-       it != resources_held_by_parent_.end();
-       ++it) {
-    if (it->id == id)
-      break;
-  }
-  DCHECK(it != resources_held_by_parent_.end());
-  ack->resources.push_back(it->ToReturnedResource());
-  resources_held_by_parent_.erase(it);
-}
-
 bool FakeOutputSurface::HasExternalStencilTest() const {
   return has_external_stencil_test_;
 }
@@ -132,4 +126,19 @@ void FakeOutputSurface::SetMemoryPolicyToSetAtBind(
   memory_policy_to_set_at_bind_.swap(memory_policy_to_set_at_bind);
 }
 
+void FakeOutputSurface::ReturnResourcesHeldByParent() {
+  if (last_sent_frame_) {
+    DelegatedFrameData* delegated_frame_data =
+        last_sent_frame_->delegated_frame_data.get();
+    if (delegated_frame_data) {
+      // Return the last frame's resources immediately.
+      CompositorFrameAck ack;
+      for (const auto& resource : resources_held_by_parent_)
+        ack.resources.push_back(resource.ToReturnedResource());
+      resources_held_by_parent_.clear();
+      client_->ReclaimResources(&ack);
+    }
+  }
+}
+
 }  // namespace cc