Add HeapCompaction FeatureList flag

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 10faf40ec121f019b0b2b6ad81b3320618a1a6bb..36e6c234adce31d31a82064cc285e9999407cde8 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -293,6 +293,9 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
       base::FeatureList::IsEnabled(
           features::kExpensiveBackgroundTimerThrottling));
 
+  if (base::FeatureList::IsEnabled(features::kHeapCompaction))
+    WebRuntimeFeatures::enableHeapCompaction(true);
+
   WebRuntimeFeatures::enableRenderingPipelineThrottling(
     base::FeatureList::IsEnabled(features::kRenderingPipelineThrottling));