Implement GCController::CollectAll

content/shell/renderer/gc_controller.cc

Index: content/shell/renderer/gc_controller.cc
diff --git a/content/shell/renderer/gc_controller.cc b/content/shell/renderer/gc_controller.cc
index ad4fa0419e2c41e50f229a3cd030030068cfcdf8..f8d3b0909c54cb16ce16a331724bc831a5e87eba 100644
--- a/content/shell/renderer/gc_controller.cc
+++ b/content/shell/renderer/gc_controller.cc
@@ -39,6 +39,7 @@ gin::ObjectTemplateBuilder GCController::GetObjectTemplateBuilder(
     v8::Isolate* isolate) {
   return gin::Wrappable<GCController>::GetObjectTemplateBuilder(isolate)
       .SetMethod("collect", &GCController::Collect)
+      .SetMethod("collectAll", &GCController::CollectAll)
       .SetMethod("minorCollect", &GCController::MinorCollect);
 }
 
@@ -47,6 +48,20 @@ void GCController::Collect(const gin::Arguments& args) {
       v8::Isolate::kFullGarbageCollection);
 }
 
+void GCController::CollectAll(const gin::Arguments& args) {
+  // In order to collect a DOM wrapper, two GC cycles are needed.
+  // In the first GC cycle, a weak callback of the DOM wrapper is called back
+  // and the weak callback disposes a persistent handle to the DOM wrapper.
+  // In the second GC cycle, the DOM wrapper is reclaimed.
+  // Given that two GC cycles are needed to collect one DOM wrapper,
+  // more than two GC cycles are needed to collect all DOM wrappers
+  // that are chained. Seven GC cycles look enough in most tests.
+  for (int i = 0; i < 7; i++) {
+    args.isolate()->RequestGarbageCollectionForTesting(
+        v8::Isolate::kFullGarbageCollection);
+  }
+}
+
 void GCController::MinorCollect(const gin::Arguments& args) {
   args.isolate()->RequestGarbageCollectionForTesting(
       v8::Isolate::kMinorGarbageCollection);