[fuchsia] runtime flag for shader warmup

Author: freiling

shell/platform/fuchsia/flutter/engine.cc

@@ -259,14 +259,14 @@ Engine::Engine(Delegate& delegate,
     }
   };
 #else
-  on_create_rasterizer = [this](flutter::Shell& shell) {
-    FML_DCHECK(surface_producer_);
-
-    WarmupSkps(
-        shell.GetDartVM()->GetConcurrentMessageLoop()->GetTaskRunner().get(),
-        shell.GetTaskRunners().GetRasterTaskRunner().get(),
-        surface_producer_.value());
-
+  on_create_rasterizer = [this, &product_config](flutter::Shell& shell) {
+    if (product_config.enable_shader_warmup()) {
+      FML_DCHECK(surface_producer_);
+      WarmupSkps(
+          shell.GetDartVM()->GetConcurrentMessageLoop()->GetTaskRunner().get(),
+          shell.GetTaskRunners().GetRasterTaskRunner().get(),
+          surface_producer_.value());
+    }
     return std::make_unique<flutter::Rasterizer>(shell);
   };
 #endif

shell/platform/fuchsia/flutter/flutter_runner_product_configuration.cc

@@ -33,6 +33,11 @@ FlutterRunnerProductConfiguration::FlutterRunnerProductConfiguration(
     if (val.IsBool())
       intercept_all_input_ = val.GetBool();
   }
+  if (document.HasMember("enable_shader_warmup")) {
+    auto& val = document["enable_shader_warmup"];
+    if (val.IsBool())
+      enable_shader_warmup_ = val.GetBool();
+  }
 #if defined(LEGACY_FUCHSIA_EMBEDDER)
   if (document.HasMember("use_legacy_renderer")) {
     auto& val = document["use_legacy_renderer"];

shell/platform/fuchsia/flutter/flutter_runner_product_configuration.h

@@ -17,6 +17,7 @@ class FlutterRunnerProductConfiguration {
   fml::TimeDelta get_vsync_offset() { return vsync_offset_; }
   uint64_t get_max_frames_in_flight() { return max_frames_in_flight_; }
   bool get_intercept_all_input() { return intercept_all_input_; }
+  bool enable_shader_warmup() { return enable_shader_warmup_; }
 #if defined(LEGACY_FUCHSIA_EMBEDDER)
   bool use_legacy_renderer() { return use_legacy_renderer_; }
 #endif
@@ -25,6 +26,7 @@ class FlutterRunnerProductConfiguration {
   fml::TimeDelta vsync_offset_ = fml::TimeDelta::Zero();
   uint64_t max_frames_in_flight_ = 3;
   bool intercept_all_input_ = false;
+  bool enable_shader_warmup_ = false;
 #if defined(LEGACY_FUCHSIA_EMBEDDER)
   bool use_legacy_renderer_ = true;
 #endif