Add a feature flag for enabling rendering pipeline throttling

content/child/runtime_features.cc

Index: content/child/runtime_features.cc
diff --git a/content/child/runtime_features.cc b/content/child/runtime_features.cc
index 80e2714318221f1df1227bc40546f5bf8e516088..ed54a5de7ec87be41848ff9b44d2f0ecabe5d73a 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -212,6 +212,9 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
   if (!base::FeatureList::IsEnabled(features::kPaintOptimizations))
     WebRuntimeFeatures::enableFeatureFromString("PaintOptimizations", false);
 
+  WebRuntimeFeatures::enableRenderingPipelineThrottling(
+    base::FeatureList::IsEnabled(features::kRenderingPipelineThrottling));
+
   // Enable explicitly enabled features, and then disable explicitly disabled
   // ones.
   if (command_line.HasSwitch(switches::kEnableBlinkFeatures)) {