Make WebTaskRunner ThreadSafeRefCounted

third_party/WebKit/Source/platform/heap/GCTaskRunner.h

Index: third_party/WebKit/Source/platform/heap/GCTaskRunner.h
diff --git a/third_party/WebKit/Source/platform/heap/GCTaskRunner.h b/third_party/WebKit/Source/platform/heap/GCTaskRunner.h
index a1db9d8bd9b3c374c5939b597d4b22999f690972..df581a834dc241a4294b0f8136bfd604e380f8d7 100644
--- a/third_party/WebKit/Source/platform/heap/GCTaskRunner.h
+++ b/third_party/WebKit/Source/platform/heap/GCTaskRunner.h
@@ -43,8 +43,8 @@ namespace blink {
 
 class MessageLoopInterruptor final : public BlinkGCInterruptor {
  public:
-  explicit MessageLoopInterruptor(WebTaskRunner* taskRunner)
-      : m_taskRunner(taskRunner) {}
+  explicit MessageLoopInterruptor(RefPtr<WebTaskRunner> taskRunner)
+      : m_taskRunner(std::move(taskRunner)) {}
 
   void requestInterrupt() override {
     // GCTask has an empty run() method. Its only purpose is to guarantee
@@ -62,7 +62,7 @@ class MessageLoopInterruptor final : public BlinkGCInterruptor {
     // conservatively enters safepoint with pointers on stack.
   }
 
-  WebTaskRunner* m_taskRunner;
+  RefPtr<WebTaskRunner> m_taskRunner;
 };
 
 class GCTaskObserver final : public WebThread::TaskObserver {