[fuchsia] shader warmup fixes

shell/platform/fuchsia/flutter/engine.cc

@@ -201,6 +201,12 @@ Engine::Engine(Delegate& delegate,
         });
       };
 
+  // Launch the engine in the appropriate configuration.
+  // Note: this initializes the Asset Manager on the global PersistantCache
+  // so it must be called before WarmupSkps() is called below.
+  auto run_configuration = flutter::RunConfiguration::InferFromSettings(
+      settings, task_runners.GetIOTaskRunner());
+
   // Setup the callback that will instantiate the platform view.
   flutter::Shell::CreateCallback<flutter::PlatformView>
       on_create_platform_view = fml::MakeCopyable(
@@ -375,10 +381,6 @@ Engine::Engine(Delegate& delegate,
     };
   }
 
-  // Launch the engine in the appropriate configuration.
-  auto run_configuration = flutter::RunConfiguration::InferFromSettings(
-      shell_->GetSettings(), shell_->GetTaskRunners().GetIOTaskRunner());
-
   auto on_run_failure = [weak = weak_factory_.GetWeakPtr()]() {
     // The engine could have been killed by the caller right after the
     // constructor was called but before it could run on the UI thread.
@@ -647,7 +649,7 @@ void Engine::WarmupSkps(fml::BasicTaskRunner* concurrent_task_runner,
 
   // tell concurrent task runner to deserialize all skps available from
   // the asset manager
-  concurrent_task_runner->PostTask([&raster_task_runner, skp_warmup_surface,
+  concurrent_task_runner->PostTask([raster_task_runner, skp_warmup_surface,
                                     &surface_producer]() {
     TRACE_DURATION("flutter", "DeserializeSkps");
     std::vector<std::unique_ptr<fml::Mapping>> skp_mappings =

shell/platform/fuchsia/flutter/tests/engine_unittests.cc

@@ -34,14 +34,22 @@ class MockTaskRunner : public fml::BasicTaskRunner {
   virtual ~MockTaskRunner() {}
 
   void PostTask(const fml::closure& task) override {
-    task_count_++;
-    task();
+    outstanding_tasks_.push(task);
   }
 
   int GetTaskCount() { return task_count_; }
 
+  void Run() {
+    while (!outstanding_tasks_.empty()) {
+      outstanding_tasks_.front()();
+      outstanding_tasks_.pop();
+      task_count_++;
+    }
+  }
+
  private:
   int task_count_ = 0;
+  std::queue<const fml::closure> outstanding_tasks_;
 };
 
 class EngineTest : public ::testing::Test {
@@ -53,15 +61,16 @@ class EngineTest : public ::testing::Test {
 
     fuchsia::ui::scenic::SessionPtr session_ptr;
     scenic::Session session(std::move(session_ptr));
-    VulkanSurfaceProducer surface_producer(&session);
+    surface_producer_ = std::make_unique<VulkanSurfaceProducer>(&session);
 
     Engine::WarmupSkps(&concurrent_task_runner_, &raster_task_runner_,
-                       surface_producer);
+                       *surface_producer_);
   }
 
  protected:
   MockTaskRunner concurrent_task_runner_;
   MockTaskRunner raster_task_runner_;
+  std::unique_ptr<VulkanSurfaceProducer> surface_producer_;
 };
 
 TEST_F(EngineTest, SkpWarmup) {
@@ -100,6 +109,8 @@ TEST_F(EngineTest, SkpWarmup) {
   PersistentCache::GetCacheForProcess()->SetAssetManager(asset_manager);
 
   WarmupSkps();
+  concurrent_task_runner_.Run();
+  raster_task_runner_.Run();
 
   EXPECT_EQ(concurrent_task_runner_.GetTaskCount(), 1);
   EXPECT_EQ(raster_task_runner_.GetTaskCount(), 1);