Make WebTaskRunner ThreadSafeRefCounted

third_party/WebKit/Source/platform/WebTaskRunner.h

Index: third_party/WebKit/Source/platform/WebTaskRunner.h
diff --git a/third_party/WebKit/Source/platform/WebTaskRunner.h b/third_party/WebKit/Source/platform/WebTaskRunner.h
index b6cf972f84d58e5b9cf7f41c16fa95d449c0da33..af5e7bf467ac2f16363853e9db0219dfaf834131 100644
--- a/third_party/WebKit/Source/platform/WebTaskRunner.h
+++ b/third_party/WebKit/Source/platform/WebTaskRunner.h
@@ -56,10 +56,9 @@ class BLINK_PLATFORM_EXPORT TaskHandle {
 };
 
 // The blink representation of a chromium SingleThreadTaskRunner.
-class BLINK_PLATFORM_EXPORT WebTaskRunner {
+class BLINK_PLATFORM_EXPORT WebTaskRunner
+    : public ThreadSafeRefCounted<WebTaskRunner> {
  public:
-  virtual ~WebTaskRunner() {}
-
   class BLINK_PLATFORM_EXPORT Task {
    public:
     virtual ~Task() {}
@@ -82,9 +81,6 @@ class BLINK_PLATFORM_EXPORT WebTaskRunner {
                                const base::Closure&,
                                double delayMs) = 0;
 
-  // Returns a clone of the WebTaskRunner.
-  virtual std::unique_ptr<WebTaskRunner> clone() = 0;
-
   // Returns true if the current thread is a thread on which a task may be run.
   // Can be called from any thread.
   virtual bool runsTasksOnCurrentThread() = 0;
@@ -133,6 +129,14 @@ class BLINK_PLATFORM_EXPORT WebTaskRunner {
   postDelayedCancellableTask(const WebTraceLocation&,
                              std::unique_ptr<WTF::Closure>,
                              long long delayMs);
+
+ protected:
+  friend ThreadSafeRefCounted<WebTaskRunner>;
+  WebTaskRunner() = default;
+  virtual ~WebTaskRunner();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WebTaskRunner);
 };
 
 }  // namespace blink