patch for flutter 1.12.13 shell/common/shell.cc

shell.cc.patch

diff --git a/shell/common/shell.cc b/shell/common/shell.cc
index bef72617c..b73018a61 100644
--- a/shell/common/shell.cc
+++ b/shell/common/shell.cc
@@ -908,15 +908,28 @@ void Shell::OnAnimatorDraw(fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline) {
       [& waiting_for_first_frame = waiting_for_first_frame_,
        &waiting_for_first_frame_condition = waiting_for_first_frame_condition_,
        rasterizer = rasterizer_->GetWeakPtr(),
-       pipeline = std::move(pipeline)]() {
-        if (rasterizer) {
-          rasterizer->Draw(pipeline);
-
-          if (waiting_for_first_frame.load()) {
-            waiting_for_first_frame.store(false);
-            waiting_for_first_frame_condition.notify_all();
+       pipeline = std::move(pipeline),
+       is_backgrounded_sync_switch = is_gpu_disabled_sync_switch_]() {
+          if (rasterizer) {
+            is_backgrounded_sync_switch->Execute(
+              fml::SyncSwitch::Handlers().SetIfFalse([&] {
+                rasterizer->Draw(pipeline);
+                if (waiting_for_first_frame.load()) {
+                  waiting_for_first_frame.store(false);
+                  waiting_for_first_frame_condition.notify_all();
+                }
+              }).SetIfTrue([&] {
+                // drop pipeline
+                Pipeline<flutter::LayerTree>::Consumer consumer =[&](std::unique_ptr<LayerTree> layer_tree) {};
+                (void)pipeline->Consume(consumer);
+
+                if (waiting_for_first_frame.load()) {
+                  waiting_for_first_frame.store(false);
+                  waiting_for_first_frame_condition.notify_all();
+                }
+              })
+            );
           }
-        }
       });
 }